在Linux中，给kernel传递参数以控制其行为总共有三种方法：

1.build kernel之时的各个configuration选项。

2.当kernel启动之时，可以参数在kernel被GRUB或LILO等启动程序调用之时传递给kernel。

3.在kernel运行时，修改/proc或/sys目录下的文件。

这里我简单讲的就是第二种方式了，kernel在grub中配置的启动参数。

首先，kernel有哪些参数呢？ 在linux的源代码中，有这样的一个文档Documentation/kernel-parameters.txt，它介绍了kernel的各个参数及其意义。

其次，kernel启动参数以空格分隔，而且是严格区分大小写的（如：mem和MEM是不一样的）。

再次，对于module特有的kernel参数写法是这样的，[module name].[parameter=XX]，例如，igb.max_vfs=7这个kernel启动参数的效果就是相当于这样来动态加载module: modprobe igb max_vfs=7

另外，kernel是怎样处理这些启动参数的呢？ 启动参数通常是这样的形式： name[=value_1][,value_2]…[,value_10]

“name”是关键字，内核用它来识别应该把”关键字”后面的值传递给谁，也就是如何处理这个值，是传递给处理进程还是作为环境变量或者抛给”init”。值的个数限制为10，你可以通过再次使用该关键字使用超过10个的参数。 首先，kernel检查关键字是不是 ‘root=’, ‘nfsroot=’, ‘nfsaddrs=’, ‘ro’, ‘rw’, ‘debug’或’init’，然后内核在bootsetups数组里搜索于该关键字相关联的已注册的处理函数，如果找到相关的已注册的处理函数，则调用这些函数并把关键字后面的值作为参数传递给这些函数。比如，你在启动时设置参数name＝a,b,c,d，内核搜索bootsetups数组，如果发现”name”已注册，则调用”name”的设置函数如name_setup()，并把a,b,c,d传递给name_setup()执行。 所有型如”name＝value”参数，如果没有被上面所述的设置函数接收，将被解释为系统启动后的环境变量，比如”TERM=vt100″启动参数就会被作为一个启动后的环境变量。所有没有被内核设置函数接收也没又被设置成环境变量的参数都将留给init进程处理，比如”single”。

下面简单总结一下我在工作中常用到的一些kernel启动参数吧。

根磁盘相关启动参数：

root #指出启动的根文件系统 如：root=/dev/sda1

ro #指定根设备在启动过程中为read-only，默认情况下一般都是这样配的

rw #和ro类似，它是规定为read-write，可写

rootfstype #根文件系统类型，如：rootfstype=ext4

Console和kernel log相关启动参数：

console #console的设备和选项，如：console=tty0 console=ttyS0

debug #enable kernel debugging 启动中的所有debug信息都会打印到console上

quiet #disable all log messages 将kernel log level设置为KERN_WARNING，在启动中只非常严重的信息

loglevel #设置默认的console日志级别，如：loglevel=7 （0~7的数字分别为：KERN_EMERG,..,KERN_DEBUG）

time #设置在每条kernel log信息前加一个时间戳

内存相关的启动参数：

mem #指定kernel使用的内存量，mem=n[KMG]

hugepages #设置大页表页（4MB大小）的最多个数，hugepages=n

CPU相关的启动参数：

mce # Enable the machine check exception feature.

nosmp #Run as a single-processor machine. 不使用SMP（多处理器）

max_cpus #max_cpus=n, SMP系统最多能使用的CPU个数（即使系统中有大于n个的CPU）

Ramdisk相关的启动参数：

initrd #指定初始化ramdisk的位置，initrd=filename

noinitrd #不使用initrd的配置，即使配置了initrd参数

初始化相关启动参数：

init #在启动时去执行的程序，init=filename，默认值为/sbin/init

PCI相关的启动参数：

pci #pci相关的选项，我常使用pci=assign_buses，也使用过pci=nomsi

SELinux相关启动参数：

enforcing #SELinux enforcing状态的开关，enforcing=0表示仅仅是记录危险而不是阻止访问，enforcing=1完全enable，默认值是0

selinux #在启动时关闭或开启SELinux，selinux=0表示关闭，selinux=1表示开启selinux

另外，还是用max_loop来指定最多可使用的回路设备。

在Redhat的系统中，还有个经常看到的kernel启动参数——rhgb，rhgb表示redhat graphics boot，就是会看到图片来代替启动过程中显示的文本信息，这些信息在启动后用dmesg也可以看到
rhgb = redhat graphical boot – This is a GUI mode booting screen with most of the information hidden while the user sees a rotating activity icon spining and brief information as to what the computer is doing.

quiet = hides the majority of boot messages before rhgb starts. These are supposed to make the common user more comfortable. They get alarmed about seeing the kernel and initializing messages, so they hide them for their comfort.

参考资料:

linux kernel documents

《Linux kernel in a nutshell》

---------------------转载内容结束------------------------------------------

    转载自：http://smilejay.com/2011/10/kernel_parameters/

    顺便贴一个内核版本为2.6.32.1的内核的kernel-parameters文档

                          Kernel Parameters                          ~~~~~~~~~~~~~~~~~The following is a consolidated list of the kernel parameters as implemented(mostly) by the __setup() macro and sorted into English Dictionary order(defined as ignoring all punctuation and sorting digits before letters in acase insensitive manner), and with descriptions where known.Module parameters for loadable modules are specified only as theparameter name with optional ‘=‘ and value as appropriate, such as:	modprobe usbcore blinkenlights=1Module parameters for modules that are built into the kernel imageare specified on the kernel command line with the module name plus‘.‘ plus parameter name, with ‘=‘ and value if appropriate, such as:	usbcore.blinkenlights=1Hyphens (dashes) and underscores are equivalent in parameter names, so	log_buf_len=1M print-fatal-signals=1can also be entered as	log-buf-len=1M print_fatal_signals=1This document may not be entirely up to date and comprehensive. The command"modinfo -p ${modulename}" shows a current list of all parameters of a loadablemodule. Loadable modules, after being loaded into the running kernel, alsoreveal their parameters in /sys/module/${modulename}/parameters/. Some of theseparameters may be changed at runtime by the command"echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".The parameters listed below are only valid if certain kernel build options wereenabled and if respective hardware is present. The text in square brackets atthe beginning of each description states the restrictions within which aparameter is applicable:	ACPI	ACPI support is enabled.	AGP	AGP (Accelerated Graphics Port) is enabled.	ALSA	ALSA sound support is enabled.	APIC	APIC support is enabled.	APM	Advanced Power Management support is enabled.	AVR32	AVR32 architecture is enabled.	AX25	Appropriate AX.25 support is enabled.	BLACKFIN Blackfin architecture is enabled.	DRM	Direct Rendering Management support is enabled.	EDD	BIOS Enhanced Disk Drive Services (EDD) is enabled	EFI	EFI Partitioning (GPT) is enabled	EIDE	EIDE/ATAPI support is enabled.	FB	The frame buffer device is enabled.	GCOV	GCOV profiling is enabled.	HW	Appropriate hardware is enabled.	IA-64	IA-64 architecture is enabled.	IMA     Integrity measurement architecture is enabled.	IOSCHED	More than one I/O scheduler is enabled.	IP_PNP	IP DHCP, BOOTP, or RARP is enabled.	ISAPNP	ISA PnP code is enabled.	ISDN	Appropriate ISDN support is enabled.	JOY	Appropriate joystick support is enabled.	KVM	Kernel Virtual Machine support is enabled.	LIBATA  Libata driver is enabled	LP	Printer support is enabled.	LOOP	Loopback device support is enabled.	M68k	M68k architecture is enabled.			These options have more detailed description inside of			Documentation/m68k/kernel-options.txt.	MCA	MCA bus support is enabled.	MDA	MDA console support is enabled.	MOUSE	Appropriate mouse support is enabled.	MSI	Message Signaled Interrupts (PCI).	MTD	MTD (Memory Technology Device) support is enabled.	NET	Appropriate network support is enabled.	NUMA	NUMA support is enabled.	GENERIC_TIME The generic timeofday code is enabled.	NFS	Appropriate NFS support is enabled.	OSS	OSS sound support is enabled.	PV_OPS	A paravirtualized kernel is enabled.	PARIDE	The ParIDE (parallel port IDE) subsystem is enabled.	PARISC	The PA-RISC architecture is enabled.	PCI	PCI bus support is enabled.	PCIE	PCI Express support is enabled.	PCMCIA	The PCMCIA subsystem is enabled.	PNP	Plug & Play support is enabled.	PPC	PowerPC architecture is enabled.	PPT	Parallel port support is enabled.	PS2	Appropriate PS/2 support is enabled.	RAM	RAM disk support is enabled.	ROOTPLUG The example Root Plug LSM is enabled.	S390	S390 architecture is enabled.	SCSI	Appropriate SCSI support is enabled.			A lot of drivers has their options described inside of			Documentation/scsi/.	SECURITY Different security models are enabled.	SELINUX SELinux support is enabled.	SERIAL	Serial support is enabled.	SH	SuperH architecture is enabled.	SMP	The kernel is an SMP kernel.	SPARC	Sparc architecture is enabled.	SWSUSP	Software suspend (hibernation) is enabled.	SUSPEND	System suspend states are enabled.	FTRACE	Function tracing enabled.	TS	Appropriate touchscreen support is enabled.	UMS	USB Mass Storage support is enabled.	USB	USB support is enabled.	USBHID	USB Human Interface Device support is enabled.	V4L	Video For Linux support is enabled.	VGA	The VGA console has been enabled.	VT	Virtual terminal support is enabled.	WDT	Watchdog support is enabled.	XT	IBM PC/XT MFM hard disk support is enabled.	X86-32	X86-32, aka i386 architecture is enabled.	X86-64	X86-64 architecture is enabled.			More X86-64 boot options can be found in			Documentation/x86/x86_64/boot-options.txt .	X86	Either 32bit or 64bit x86 (same as X86-32+X86-64)In addition, the following text indicates that the option:	BUGS=	Relates to possible processor bugs on the said processor.	KNL	Is a kernel start-up parameter.	BOOT	Is a boot loader parameter.Parameters denoted with BOOT are actually interpreted by the bootloader, and have no meaning to the kernel directly.Do not modify the syntax of boot loader parameters without extremeneed or coordination with <Documentation/x86/boot.txt>.There are also arch-specific kernel-parameters not documented here.See for example <Documentation/x86/x86_64/boot-options.txt>.Note that ALL kernel parameters listed below are CASE SENSITIVE, and thata trailing = on the name of any parameter states that that parameter willbe entered as an environment variable, whereas its absence indicates thatit will appear as a kernel argument readable via /proc/cmdline by programsrunning once the system is up.The number of kernel parameters is not limited, but the length of thecomplete command line (parameters including spaces etc.) is limited toa fixed number of characters. This limit depends on the architectureand is between 256 and 4096 characters. It is defined in the file./include/asm/setup.h as COMMAND_LINE_SIZE.	acpi=		[HW,ACPI,X86]			Advanced Configuration and Power Interface			Format: { force | off | ht | strict | noirq | rsdt }			force -- enable ACPI if default was off			off -- disable ACPI if default was on			noirq -- do not use ACPI for IRQ routing			ht -- run only enough ACPI to enable Hyper Threading			strict -- Be less tolerant of platforms that are not				strictly ACPI specification compliant.			rsdt -- prefer RSDT over (default) XSDT			See also Documentation/power/pm.txt, pci=noacpi	acpi_apic_instance=	[ACPI, IOAPIC]			Format: <int>			2: use 2nd APIC table, if available			1,0: use 1st APIC table			default: 0	acpi_backlight=	[HW,ACPI]			acpi_backlight=vendor			acpi_backlight=video			If set to vendor, prefer vendor specific driver			(e.g. thinkpad_acpi, sony_acpi, etc.) instead			of the ACPI video.ko driver.	acpi.debug_layer=	[HW,ACPI,ACPI_DEBUG]	acpi.debug_level=	[HW,ACPI,ACPI_DEBUG]			Format: <int>			CONFIG_ACPI_DEBUG must be enabled to produce any ACPI			debug output.  Bits in debug_layer correspond to a			_COMPONENT in an ACPI source file, e.g.,			    #define _COMPONENT ACPI_PCI_COMPONENT			Bits in debug_level correspond to a level in			ACPI_DEBUG_PRINT statements, e.g.,			    ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...			The debug_level mask defaults to "info".  See			Documentation/acpi/debug.txt for more information about			debug layers and levels.			Enable processor driver info messages:			    acpi.debug_layer=0x20000000			Enable PCI/PCI interrupt routing info messages:			    acpi.debug_layer=0x400000			Enable AML "Debug" output, i.e., stores to the Debug			object while interpreting AML:			    acpi.debug_layer=0xffffffff acpi.debug_level=0x2			Enable all messages related to ACPI hardware:			    acpi.debug_layer=0x2 acpi.debug_level=0xffffffff			Some values produce so much output that the system is			unusable.  The "log_buf_len" parameter may be useful			if you need to capture more output.	acpi_display_output=	[HW,ACPI]			acpi_display_output=vendor			acpi_display_output=video			See above.	acpi_irq_balance [HW,ACPI]			ACPI will balance active IRQs			default in APIC mode	acpi_irq_nobalance [HW,ACPI]			ACPI will not move active IRQs (default)			default in PIC mode	acpi_irq_isa=	[HW,ACPI] If irq_balance, mark listed IRQs used by ISA			Format: <irq>,<irq>...	acpi_irq_pci=	[HW,ACPI] If irq_balance, clear listed IRQs for			use by PCI			Format: <irq>,<irq>...	acpi_no_auto_ssdt	[HW,ACPI] Disable automatic loading of SSDT	acpi_os_name=	[HW,ACPI] Tell ACPI BIOS the name of the OS			Format: To spoof as Windows 98: ="Microsoft Windows"	acpi_osi=	[HW,ACPI] Modify list of supported OS interface strings			acpi_osi="string1"	# add string1 -- only one string			acpi_osi="!string2"	# remove built-in string2			acpi_osi=		# disable all strings	acpi_pm_good	[X86]			Override the pmtimer bug detection: force the kernel			to assume that this machine‘s pmtimer latches its value			and always returns good values.	acpi_sci=	[HW,ACPI] ACPI System Control Interrupt trigger mode			Format: { level | edge | high | low }	acpi_serialize	[HW,ACPI] force serialization of AML methods	acpi_skip_timer_override [HW,ACPI]			Recognize and ignore IRQ0/pin2 Interrupt Override.			For broken nForce2 BIOS resulting in XT-PIC timer.	acpi_sleep=	[HW,ACPI] Sleep options			Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,				  old_ordering, s4_nonvs }			See Documentation/power/video.txt for information on			s3_bios and s3_mode.			s3_beep is for debugging; it makes the PC‘s speaker beep			as soon as the kernel‘s real-mode entry point is called.			s4_nohwsig prevents ACPI hardware signature from being			used during resume from hibernation.			old_ordering causes the ACPI 1.0 ordering of the _PTS			control method, with respect to putting devices into			low power states, to be enforced (the ACPI 2.0 ordering			of _PTS is used by default).			s4_nonvs prevents the kernel from saving/restoring the			ACPI NVS memory during hibernation.	acpi_use_timer_override [HW,ACPI]			Use timer override. For some broken Nvidia NF5 boards			that require a timer override, but don‘t have HPET	acpi_enforce_resources=	[ACPI]			{ strict | lax | no }			Check for resource conflicts between native drivers			and ACPI OperationRegions (SystemIO and SystemMemory			only). IO ports and memory declared in ACPI might be			used by the ACPI subsystem in arbitrary AML code and			can interfere with legacy drivers.			strict (default): access to resources claimed by ACPI			is denied; legacy drivers trying to access reserved			resources will fail to bind to device using them.			lax: access to resources claimed by ACPI is allowed;			legacy drivers trying to access reserved resources			will bind successfully but a warning message is logged.			no: ACPI OperationRegions are not marked as reserved,			no further checks are performed.	ad1848=		[HW,OSS]			Format: <io>,<irq>,<dma>,<dma2>,<type>	add_efi_memmap	[EFI; X86] Include EFI memory map in			kernel‘s map of available physical RAM.	advansys=	[HW,SCSI]			See header of drivers/scsi/advansys.c.	advwdt=		[HW,WDT] Advantech WDT			Format: <iostart>,<iostop>	aedsp16=	[HW,OSS] Audio Excel DSP 16			Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>			See also header of sound/oss/aedsp16.c.	agp=		[AGP]			{ off | try_unsupported }			off: disable AGP support			try_unsupported: try to drive unsupported chipsets				(may crash computer or cause data corruption)	aha152x=	[HW,SCSI]			See Documentation/scsi/aha152x.txt.	aha1542=	[HW,SCSI]			Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]	aic7xxx=	[HW,SCSI]			See Documentation/scsi/aic7xxx.txt.	aic79xx=	[HW,SCSI]			See Documentation/scsi/aic79xx.txt.	amd_iommu=	[HW,X86-84]			Pass parameters to the AMD IOMMU driver in the system.			Possible values are:			isolate - enable device isolation (each device, as far			          as possible, will get its own protection			          domain) [default]			share - put every device behind one IOMMU into the				same protection domain			fullflush - enable flushing of IO/TLB entries when				    they are unmapped. Otherwise they are				    flushed before they will be reused, which				    is a lot of faster	amijoy.map=	[HW,JOY] Amiga joystick support			Map of devices attached to JOY0DAT and JOY1DAT			Format: <a>,<b>			See also Documentation/kernel/input/joystick.txt	analog.map=	[HW,JOY] Analog joystick and gamepad support			Specifies type or capabilities of an analog joystick			connected to one of 16 gameports			Format: <type1>,<type2>,..<type16>	apc=		[HW,SPARC]			Power management functions (SPARCstation-4/5 + deriv.)			Format: noidle			Disable APC CPU standby support. SPARCstation-Fox does			not play well with APC CPU idle - disable it if you have			APC and your system crashes randomly.	apic=		[APIC,X86-32] Advanced Programmable Interrupt Controller			Change the output verbosity whilst booting			Format: { quiet (default) | verbose | debug }			Change the amount of debugging information output			when initialising the APIC and IO-APIC components.	apm=		[APM] Advanced Power Management			See header of arch/x86/kernel/apm_32.c.	arcrimi=	[HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards			Format: <io>,<irq>,<nodeID>	ataflop=	[HW,M68k]	atarimouse=	[HW,MOUSE] Atari Mouse	atascsi=	[HW,SCSI] Atari SCSI	atkbd.extra=	[HW] Enable extra LEDs and keys on IBM RapidAccess,			EzKey and similar keyboards	atkbd.reset=	[HW] Reset keyboard during initialization	atkbd.set=	[HW] Select keyboard code set			Format: <int> (2 = AT (default), 3 = PS/2)	atkbd.scroll=	[HW] Enable scroll wheel on MS Office and similar			keyboards	atkbd.softraw=	[HW] Choose between synthetic and real raw mode			Format: <bool> (0 = real, 1 = synthetic (default))	atkbd.softrepeat= [HW]			Use software keyboard repeat	autotest	[IA64]	baycom_epp=	[HW,AX25]			Format: <io>,<mode>	baycom_par=	[HW,AX25] BayCom Parallel Port AX.25 Modem			Format: <io>,<mode>			See header of drivers/net/hamradio/baycom_par.c.	baycom_ser_fdx=	[HW,AX25]			BayCom Serial Port AX.25 Modem (Full Duplex Mode)			Format: <io>,<irq>,<mode>[,<baud>]			See header of drivers/net/hamradio/baycom_ser_fdx.c.	baycom_ser_hdx=	[HW,AX25]			BayCom Serial Port AX.25 Modem (Half Duplex Mode)			Format: <io>,<irq>,<mode>			See header of drivers/net/hamradio/baycom_ser_hdx.c.	boot_delay=	Milliseconds to delay each printk during boot.			Values larger than 10 seconds (10000) are changed to			no delay (0).			Format: integer	bootmem_debug	[KNL] Enable bootmem allocator debug messages.	bttv.card=	[HW,V4L] bttv (bt848 + bt878 based grabber cards)	bttv.radio=	Most important insmod options are available as			kernel args too.	bttv.pll=	See Documentation/video4linux/bttv/Insmod-options	bttv.tuner=	and Documentation/video4linux/bttv/CARDLIST	BusLogic=	[HW,SCSI]			See drivers/scsi/BusLogic.c, comment before function			BusLogic_ParseDriverOptions().	c101=		[NET] Moxa C101 synchronous serial card	cachesize=	[BUGS=X86-32] Override level 2 CPU cache size detection.			Sometimes CPU hardware bugs make them report the cache			size incorrectly. The kernel will attempt work arounds			to fix known problems, but for some CPUs it is not			possible to determine what the correct size should be.			This option provides an override for these situations.	capability.disable=			[SECURITY] Disable capabilities.  This would normally			be used only if an alternative security model is to be			configured.  Potentially dangerous and should only be			used if you are entirely sure of the consequences.	ccw_timeout_log [S390]			See Documentation/s390/CommonIO for details.	cgroup_disable= [KNL] Disable a particular controller			Format: {name of the controller(s) to disable}				{Currently supported controllers - "memory"}	checkreqprot	[SELINUX] Set initial checkreqprot flag value.			Format: { "0" | "1" }			See security/selinux/Kconfig help text.			0 -- check protection applied by kernel (includes				any implied execute protection).			1 -- check protection requested by application.			Default value is set via a kernel config option.			Value can be changed at runtime via				/selinux/checkreqprot.	cio_ignore=	[S390]			See Documentation/s390/CommonIO for details.	clock=		[BUGS=X86-32, HW] gettimeofday clocksource override.			[Deprecated]			Forces specified clocksource (if available) to be used			when calculating gettimeofday(). If specified			clocksource is not available, it defaults to PIT.			Format: { pit | tsc | cyclone | pmtmr }	clocksource=	[GENERIC_TIME] Override the default clocksource			Format: <string>			Override the default clocksource and use the clocksource			with the name specified.			Some clocksource names to choose from, depending on			the platform:			[all] jiffies (this is the base, fallback clocksource)			[ACPI] acpi_pm			[ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,				pxa_timer,timer3,32k_counter,timer0_1			[AVR32] avr32			[X86-32] pit,hpet,tsc,vmi-timer;				scx200_hrt on Geode; cyclone on IBM x440			[MIPS] MIPS			[PARISC] cr16			[S390] tod			[SH] SuperH			[SPARC64] tick			[X86-64] hpet,tsc	clearcpuid=BITNUM [X86]			Disable CPUID feature X for the kernel. See			arch/x86/include/asm/cpufeature.h for the valid bit			numbers. Note the Linux specific bits are not necessarily			stable over kernel options, but the vendor specific			ones should be.			Also note that user programs calling CPUID directly			or using the feature without checking anything			will still see it. This just prevents it from			being used by the kernel or shown in /proc/cpuinfo.			Also note the kernel might malfunction if you disable			some critical bits.	cmo_free_hint=	[PPC] Format: { yes | no }			Specify whether pages are marked as being inactive			when they are freed.  This is used in CMO environments			to determine OS memory pressure for page stealing by			a hypervisor.			Default: yes	code_bytes	[X86] How many bytes of object code to print			in an oops report.			Range: 0 - 8192			Default: 64	com20020=	[HW,NET] ARCnet - COM20020 chipset			Format:			<io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]	com90io=	[HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)			Format: <io>[,<irq>]	com90xx=	[HW,NET]			ARCnet - COM90xx chipset (memory-mapped buffers)			Format: <io>[,<irq>[,<memstart>]]	condev=		[HW,S390] console device	conmode=	console=	[KNL] Output console device and options.		tty<n>	Use the virtual console device <n>.		ttyS<n>[,options]		ttyUSB0[,options]			Use the specified serial port.  The options are of			the form "bbbbpnf", where "bbbb" is the baud rate,			"p" is parity ("n", "o", or "e"), "n" is number of			bits, and "f" is flow control ("r" for RTS or			omit it).  Default is "9600n8".			See Documentation/serial-console.txt for more			information.  See			Documentation/networking/netconsole.txt for an			alternative.		uart[8250],io,<addr>[,options]		uart[8250],mmio,<addr>[,options]			Start an early, polled-mode console on the 8250/16550			UART at the specified I/O port or MMIO address,			switching to the matching ttyS device later.  The			options are the same as for ttyS, above.                If the device connected to the port is not a TTY but a braille                device, prepend "brl," before the device type, for instance			console=brl,ttyS0		For now, only VisioBraille is supported.	consoleblank=	[KNL] The console blank (screen saver) timeout in			seconds. Defaults to 10*60 = 10mins. A value of 0			disables the blank timer.	coredump_filter=			[KNL] Change the default value for			/proc/<pid>/coredump_filter.			See also Documentation/filesystems/proc.txt.	cpcihp_generic=	[HW,PCI] Generic port I/O CompactPCI driver			Format:			<first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]	crashkernel=nn[KMG]@ss[KMG]			[KNL] Reserve a chunk of physical memory to			hold a kernel to switch to with kexec on panic.	crashkernel=range1:size1[,range2:size2,...][@offset]			[KNL] Same as above, but depends on the memory			in the running system. The syntax of range is			start-[end] where start and end are both			a memory unit (amount[KMG]). See also			Documentation/kdump/kdump.txt for a example.	cs89x0_dma=	[HW,NET]			Format: <dma>	cs89x0_media=	[HW,NET]			Format: { rj45 | aui | bnc }	dasd=		[HW,NET]			See header of drivers/s390/block/dasd_devmap.c.	db9.dev[2|3]=	[HW,JOY] Multisystem joystick support via parallel port			(one device per port)			Format: <port#>,<type>			See also Documentation/input/joystick-parport.txt	debug		[KNL] Enable kernel debugging (events log level).	debug_locks_verbose=			[KNL] verbose self-tests			Format=<0|1>			Print debugging info while doing the locking API			self-tests.			We default to 0 (no extra messages), setting it to			1 will print _a lot_ more information - normally			only useful to kernel developers.	debug_objects	[KNL] Enable object debugging	no_debug_objects			[KNL] Disable object debugging	debugpat	[X86] Enable PAT debugging	decnet.addr=	[HW,NET]			Format: <area>[,<node>]			See also Documentation/networking/decnet.txt.	default_hugepagesz=			[same as hugepagesz=] The size of the default			HugeTLB page size. This is the size represented by			the legacy /proc/ hugepages APIs, used for SHM, and			default size when mounting hugetlbfs filesystems.			Defaults to the default architecture‘s huge page size			if not specified.	dhash_entries=	[KNL]			Set number of hash buckets for dentry cache.	digi=		[HW,SERIAL]			IO parameters + enable/disable command.	digiepca=	[HW,SERIAL]			See drivers/char/README.epca and			Documentation/serial/digiepca.txt.	disable_mtrr_cleanup [X86]			The kernel tries to adjust MTRR layout from continuous			to discrete, to make X server driver able to add WB			entry later. This parameter disables that.	disable_mtrr_trim [X86, Intel and AMD only]			By default the kernel will trim any uncacheable			memory out of your available memory pool based on			MTRR settings.  This parameter disables that behavior,			possibly causing your machine to run very slowly.	disable_timer_pin_1 [X86]			Disable PIN 1 of APIC timer			Can be useful to work around chipset bugs.	dmasound=	[HW,OSS] Sound subsystem buffers	dma_debug=off	If the kernel is compiled with DMA_API_DEBUG support,			this option disables the debugging code at boot.	dma_debug_entries=<number>			This option allows to tune the number of preallocated			entries for DMA-API debugging code. One entry is			required per DMA-API allocation. Use this if the			DMA-API debugging code disables itself because the			architectural default is too low.	dma_debug_driver=<driver_name>			With this option the DMA-API debugging driver			filter feature can be enabled at boot time. Just			pass the driver to filter for as the parameter.			The filter can be disabled or changed to another			driver later using sysfs.	dscc4.setup=	[NET]	dtc3181e=	[HW,SCSI]	dynamic_printk	Enables pr_debug()/dev_dbg() calls if			CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.			These can also be switched on/off via			<debugfs>/dynamic_printk/modules	earlycon=	[KNL] Output early console device and options.		uart[8250],io,<addr>[,options]		uart[8250],mmio,<addr>[,options]			Start an early, polled-mode console on the 8250/16550			UART at the specified I/O port or MMIO address.			The options are the same as for ttyS, above.	earlyprintk=	[X86,SH,BLACKFIN]			earlyprintk=vga			earlyprintk=serial[,ttySn[,baudrate]]			earlyprintk=ttySn[,baudrate]			earlyprintk=dbgp[debugController#]			Append ",keep" to not disable it when the real console			takes over.			Only vga or serial or usb debug port at a time.			Currently only ttyS0 and ttyS1 are supported.			Interaction with the standard serial driver is not			very good.			The VGA output is eventually overwritten by the real			console.	eata=		[HW,SCSI]	edd=		[EDD]			Format: {"off" | "on" | "skip[mbr]"}	eisa_irq_edge=	[PARISC,HW]			See header of drivers/parisc/eisa.c.	elanfreq=	[X86-32]			See comment before function elanfreq_setup() in			arch/x86/kernel/cpu/cpufreq/elanfreq.c.	elevator=	[IOSCHED]			Format: {"anticipatory" | "cfq" | "deadline" | "noop"}			See Documentation/block/as-iosched.txt and			Documentation/block/deadline-iosched.txt for details.	elfcorehdr=	[IA64,PPC,SH,X86]			Specifies physical address of start of kernel core			image elf header. Generally kexec loader will			pass this option to capture kernel.			See Documentation/kdump/kdump.txt for details.	enable_mtrr_cleanup [X86]			The kernel tries to adjust MTRR layout from continuous			to discrete, to make X server driver able to add WB			entry later. This parameter enables that.	enable_timer_pin_1 [X86]			Enable PIN 1 of APIC timer			Can be useful to work around chipset bugs			(in particular on some ATI chipsets).			The kernel tries to set a reasonable default.	enforcing	[SELINUX] Set initial enforcing status.			Format: {"0" | "1"}			See security/selinux/Kconfig help text.			0 -- permissive (log only, no denials).			1 -- enforcing (deny and log).			Default value is 0.			Value can be changed at runtime via /selinux/enforce.	ether=		[HW,NET] Ethernet cards parameters			This option is obsoleted by the "netdev=" option, which			has equivalent usage. See its documentation for details.	eurwdt=		[HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.			Format: <io>[,<irq>]	failslab=	fail_page_alloc=	fail_make_request=[KNL]			General fault injection mechanism.			Format: <interval>,<probability>,<space>,<times>			See also /Documentation/fault-injection/.	fd_mcs=		[HW,SCSI]			See header of drivers/scsi/fd_mcs.c.	fdomain=	[HW,SCSI]			See header of drivers/scsi/fdomain.c.	floppy=		[HW]			See Documentation/blockdev/floppy.txt.	force_pal_cache_flush			[IA-64] Avoid check_sal_cache_flush which may hang on			buggy SAL_CACHE_FLUSH implementations. Using this			parameter will force ia64_sal_cache_flush to call			ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.	ftrace=[tracer]			[FTRACE] will set and start the specified tracer			as early as possible in order to facilitate early			boot debugging.	ftrace_dump_on_oops			[FTRACE] will dump the trace buffers on oops.	ftrace_filter=[function-list]			[FTRACE] Limit the functions traced by the function			tracer at boot up. function-list is a comma separated			list of functions. This list can be changed at run			time by the set_ftrace_filter file in the debugfs			tracing directory. 	ftrace_notrace=[function-list]			[FTRACE] Do not trace the functions specified in			function-list. This list can be changed at run time			by the set_ftrace_notrace file in the debugfs			tracing directory.	gamecon.map[2|3]=			[HW,JOY] Multisystem joystick and NES/SNES/PSX pad			support via parallel port (up to 5 devices per port)			Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>			See also Documentation/input/joystick-parport.txt	gamma=		[HW,DRM]	gart_fix_e820=  [X86_64] disable the fix e820 for K8 GART			Format: off | on			default: on	gcov_persist=	[GCOV] When non-zero (default), profiling data for			kernel modules is saved and remains accessible via			debugfs, even when the module is unloaded/reloaded.			When zero, profiling data is discarded and associated			debugfs files are removed at module unload time.	gdth=		[HW,SCSI]			See header of drivers/scsi/gdth.c.	gpt		[EFI] Forces disk with valid GPT signature but			invalid Protective MBR to be treated as GPT.	gvp11=		[HW,SCSI]	hashdist=	[KNL,NUMA] Large hashes allocated during boot			are distributed across NUMA nodes.  Defaults on			for 64bit NUMA, off otherwise.			Format: 0 | 1 (for off | on)	hcl=		[IA-64] SGI‘s Hardware Graph compatibility layer	hd=		[EIDE] (E)IDE hard drive subsystem geometry			Format: <cyl>,<head>,<sect>	highmem=nn[KMG]	[KNL,BOOT] forces the highmem zone to have an exact			size of <nn>. This works even on boxes that have no			highmem otherwise. This also works to reduce highmem			size on bigger boxes.	highres=	[KNL] Enable/disable high resolution timer mode.			Valid parameters: "on", "off"			Default: "on"	hisax=		[HW,ISDN]			See Documentation/isdn/README.HiSax.	hlt		[BUGS=ARM,SH]	hpet=		[X86-32,HPET] option to control HPET usage			Format: { enable (default) | disable | force |				verbose }			disable: disable HPET and use PIT instead			force: allow force enabled of undocumented chips (ICH4,				VIA, nVidia)			verbose: show contents of HPET registers during setup	hugepages=	[HW,X86-32,IA-64] HugeTLB pages to allocate at boot.	hugepagesz=	[HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.			On x86-64 and powerpc, this option can be specified			multiple times interleaved with hugepages= to reserve			huge pages of different sizes. Valid pages sizes on			x86-64 are 2M (when the CPU supports "pse") and 1G			(when the CPU supports the "pdpe1gb" cpuinfo flag)			Note that 1GB pages can only be allocated at boot time			using hugepages= and not freed afterwards.	hvc_iucv=	[S390] Number of z/VM IUCV hypervisor console (HVC)			       terminal devices. Valid values: 0..8	hvc_iucv_allow=	[S390] Comma-separated list of z/VM user IDs.			       If specified, z/VM IUCV HVC accepts connections			       from listed z/VM user IDs only.	i2c_bus=	[HW] Override the default board specific I2C bus speed			     or register an additional I2C bus that is not			     registered from board initialization code.			     Format:			     <bus_id>,<clkrate>	i8042.debug	[HW] Toggle i8042 debug mode	i8042.direct	[HW] Put keyboard port into non-translated mode	i8042.dumbkbd	[HW] Pretend that controller can only read data from			     keyboard and cannot control its state			     (Don‘t attempt to blink the leds)	i8042.noaux	[HW] Don‘t check for auxiliary (== mouse) port	i8042.nokbd	[HW] Don‘t check/create keyboard port	i8042.noloop	[HW] Disable the AUX Loopback command while probing			     for the AUX port	i8042.nomux	[HW] Don‘t check presence of an active multiplexing			     controller	i8042.nopnp	[HW] Don‘t use ACPIPnP / PnPBIOS to discover KBD/AUX			     controllers	i8042.panicblink=			[HW] Frequency with which keyboard LEDs should blink			     when kernel panics (default is 0.5 sec)	i8042.reset	[HW] Reset the controller during init and cleanup	i8042.unlock	[HW] Unlock (ignore) the keylock	i810=		[HW,DRM]	i8k.ignore_dmi	[HW] Continue probing hardware even if DMI data			indicates that the driver is running on unsupported			hardware.	i8k.force	[HW] Activate i8k driver even if SMM BIOS signature			does not match list of supported models.	i8k.power_status			[HW] Report power status in /proc/i8k			(disabled by default)	i8k.restricted	[HW] Allow controlling fans only if SYS_ADMIN			capability is set.	ibmmcascsi=	[HW,MCA,SCSI] IBM MicroChannel SCSI adapter			See Documentation/mca.txt.	icn=		[HW,ISDN]			Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]	ide-core.nodma=	[HW] (E)IDE subsystem			Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc			.vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr			.cdrom .chs .ignore_cable are additional options			See Documentation/ide/ide.txt.	ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem			Claim all unknown PCI IDE storage controllers.	idle=		[X86]			Format: idle=poll, idle=mwait, idle=halt, idle=nomwait			Poll forces a polling idle loop that can slightly			improve the performance of waking up a idle CPU, but			will use a lot of power and make the system run hot.			Not recommended.			idle=mwait: On systems which support MONITOR/MWAIT but			the kernel chose to not use it because it doesn‘t save			as much power as a normal idle loop, use the			MONITOR/MWAIT idle loop anyways. Performance should be			the same as idle=poll.			idle=halt: Halt is forced to be used for CPU idle.			In such case C2/C3 won‘t be used again.			idle=nomwait: Disable mwait for CPU C-states	ignore_loglevel	[KNL]			Ignore loglevel setting - this will print /all/			kernel messages to the console. Useful for debugging.	ihash_entries=	[KNL]			Set number of hash buckets for inode cache.	ima_audit=	[IMA]			Format: { "0" | "1" }			0 -- integrity auditing messages. (Default)			1 -- enable informational integrity auditing messages.	ima_hash=	[IMA]			Format: { "sha1" | "md5" }			default: "sha1"	ima_tcb		[IMA]			Load a policy which meets the needs of the Trusted			Computing Base.  This means IMA will measure all			programs exec‘d, files mmap‘d for exec, and all files			opened for read by uid=0.	in2000=		[HW,SCSI]			See header of drivers/scsi/in2000.c.	init=		[KNL]			Format: <full_path>			Run specified binary instead of /sbin/init as init			process.	initcall_debug	[KNL] Trace initcalls as they are executed.  Useful			for working out where the kernel is dying during			startup.	initrd=		[BOOT] Specify the location of the initial ramdisk	inport.irq=	[HW] Inport (ATI XL and Microsoft) busmouse driver			Format: <irq>	intel_iommu=	[DMAR] Intel IOMMU driver (DMAR) option		on			Enable intel iommu driver.		off			Disable intel iommu driver.		igfx_off [Default Off]			By default, gfx is mapped as normal device. If a gfx			device has a dedicated DMAR unit, the DMAR unit is			bypassed by not enabling DMAR with this option. In			this case, gfx device will use physical address for			DMA.		forcedac [x86_64]			With this option iommu will not optimize to look			for io virtual address below 32 bit forcing dual			address cycle on pci bus for cards supporting greater			than 32 bit addressing. The default is to look			for translation below 32 bit and if not available			then look in the higher range.		strict [Default Off]			With this option on every unmap_single operation will			result in a hardware IOTLB flush operation as opposed			to batching them for performance.	inttest=	[IA64]	iomem=		Disable strict checking of access to MMIO memory		strict	regions from userspace.		relaxed	iommu=		[x86]		off		force		noforce		biomerge		panic		nopanic		merge		nomerge		forcesac		soft		pt	[x86, IA64]	io7=		[HW] IO7 for Marvel based alpha systems			See comment before marvel_specify_io7 in			arch/alpha/kernel/core_marvel.c.	io_delay=	[X86] I/O delay method		0x80			Standard port 0x80 based delay		0xed			Alternate port 0xed based delay (needed on some systems)		udelay			Simple two microseconds delay		none			No delay	ip=		[IP_PNP]			See Documentation/filesystems/nfsroot.txt.	ip2=		[HW] Set IO/IRQ pairs for up to 4 IntelliPort boards			See comment before ip2_setup() in			drivers/char/ip2/ip2base.c.	ips=		[HW,SCSI] Adaptec / IBM ServeRAID controller			See header of drivers/scsi/ips.c.	irqfixup	[HW]			When an interrupt is not handled search all handlers			for it. Intended to get systems with badly broken			firmware running.	irqpoll		[HW]			When an interrupt is not handled search all handlers			for it. Also check all handlers each timer			interrupt. Intended to get systems with badly broken			firmware running.	isapnp=		[ISAPNP]			Format: <RDP>,<reset>,<pci_scan>,<verbosity>	isolcpus=	[KNL,SMP] Isolate CPUs from the general scheduler.			Format:			<cpu number>,...,<cpu number>			or			<cpu number>-<cpu number>			(must be a positive range in ascending order)			or a mixture			<cpu number>,...,<cpu number>-<cpu number>			This option can be used to specify one or more CPUs			to isolate from the general SMP balancing and scheduling			algorithms. You can move a process onto or off an			"isolated" CPU via the CPU affinity syscalls or cpuset.			<cpu number> begins at 0 and the maximum value is			"number of CPUs in system - 1".			This option is the preferred way to isolate CPUs. The			alternative -- manually setting the CPU mask of all			tasks in the system -- can cause problems and			suboptimal load balancer performance.	iucv=		[HW,NET]	js=		[HW,JOY] Analog joystick			See Documentation/input/joystick.txt.	keepinitrd	[HW,ARM]	kernelcore=nn[KMG]	[KNL,X86,IA-64,PPC] This parameter			specifies the amount of memory usable by the kernel			for non-movable allocations.  The requested amount is			spread evenly throughout all nodes in the system. The			remaining memory in each node is used for Movable			pages. In the event, a node is too small to have both			kernelcore and Movable pages, kernelcore pages will			take priority and other nodes will have a larger number			of kernelcore pages.  The Movable zone is used for the			allocation of pages that may be reclaimed or moved			by the page migration subsystem.  This means that			HugeTLB pages may not be allocated from this zone.			Note that allocations like PTEs-from-HighMem still			use the HighMem zone if it exists, and the Normal			zone if it does not.	kgdboc=		[HW] kgdb over consoles.			Requires a tty driver that supports console polling.			(only serial supported for now)			Format: <serial_device>[,baud]	kmac=		[MIPS] korina ethernet MAC address.			Configure the RouterBoard 532 series on-chip			Ethernet adapter MAC address.	kmemleak=	[KNL] Boot-time kmemleak enable/disable			Valid arguments: on, off			Default: on	kstack=N	[X86] Print N words from the kernel stack			in oops dumps.	kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.			Default is 0 (don‘t ignore, but inject #GP)	kvm.oos_shadow=	[KVM] Disable out-of-sync shadow paging.			Default is 1 (enabled)	kvm-amd.nested=	[KVM,AMD] Allow nested virtualization in KVM/SVM.			Default is 0 (off)	kvm-amd.npt=	[KVM,AMD] Disable nested paging (virtualized MMU)			for all guests.			Default is 1 (enabled) if in 64bit or 32bit-PAE mode	kvm-intel.bypass_guest_pf=			[KVM,Intel] Disables bypassing of guest page faults			on Intel chips. Default is 1 (enabled)	kvm-intel.ept=	[KVM,Intel] Disable extended page tables			(virtualized MMU) support on capable Intel chips.			Default is 1 (enabled)	kvm-intel.emulate_invalid_guest_state=			[KVM,Intel] Enable emulation of invalid guest states			Default is 0 (disabled)	kvm-intel.flexpriority=			[KVM,Intel] Disable FlexPriority feature (TPR shadow).			Default is 1 (enabled)	kvm-intel.unrestricted_guest=			[KVM,Intel] Disable unrestricted guest feature			(virtualized real and unpaged mode) on capable			Intel chips. Default is 1 (enabled)	kvm-intel.vpid=	[KVM,Intel] Disable Virtual Processor Identification			feature (tagged TLBs) on capable Intel chips.			Default is 1 (enabled)	l2cr=		[PPC]	l3cr=		[PPC]	lapic		[X86-32,APIC] Enable the local APIC even if BIOS			disabled it.	lapic_timer_c2_ok	[X86,APIC] trust the local apic timer			in C2 power state.	libata.dma=	[LIBATA] DMA control			libata.dma=0	  Disable all PATA and SATA DMA			libata.dma=1	  PATA and SATA Disk DMA only			libata.dma=2	  ATAPI (CDROM) DMA only			libata.dma=4	  Compact Flash DMA only 			Combinations also work, so libata.dma=3 enables DMA			for disks and CDROMs, but not CFs.		libata.ignore_hpa=	[LIBATA] Ignore HPA limit			libata.ignore_hpa=0	  keep BIOS limits (default)			libata.ignore_hpa=1	  ignore limits, using full disk	libata.noacpi	[LIBATA] Disables use of ACPI in libata suspend/resume			when set.			Format: <int>	libata.force=	[LIBATA] Force configurations.  The format is comma			separated list of "[ID:]VAL" where ID is			PORT[:DEVICE].  PORT and DEVICE are decimal numbers			matching port, link or device.  Basically, it matches			the ATA ID string printed on console by libata.  If			the whole ID part is omitted, the last PORT and DEVICE			values are used.  If ID hasn‘t been specified yet, the			configuration applies to all ports, links and devices.			If only DEVICE is omitted, the parameter applies to			the port and all links and devices behind it.  DEVICE			number of 0 either selects the first device or the			first fan-out link behind PMP device.  It does not			select the host link.  DEVICE number of 15 selects the			host link and device attached to it.			The VAL specifies the configuration to force.  As long			as there‘s no ambiguity shortcut notation is allowed.			For example, both 1.5 and 1.5G would work for 1.5Gbps.			The following configurations can be forced.			* Cable type: 40c, 80c, short40c, unk, ign or sata.			  Any ID with matching PORT is used.			* SATA link speed limit: 1.5Gbps or 3.0Gbps.			* Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].			  udma[/][16,25,33,44,66,100,133] notation is also			  allowed.			* [no]ncq: Turn on or off NCQ.			* nohrst, nosrst, norst: suppress hard, soft                          and both resets.			If there are multiple matching configurations changing			the same attribute, the last one is used.	lmb=debug	[KNL] Enable lmb debug messages.	load_ramdisk=	[RAM] List of ramdisks to load from floppy			See Documentation/blockdev/ramdisk.txt.	lockd.nlm_grace_period=P  [NFS] Assign grace period.			Format: <integer>	lockd.nlm_tcpport=N	[NFS] Assign TCP port.			Format: <integer>	lockd.nlm_timeout=T	[NFS] Assign timeout value.			Format: <integer>	lockd.nlm_udpport=M	[NFS] Assign UDP port.			Format: <integer>	logibm.irq=	[HW,MOUSE] Logitech Bus Mouse Driver			Format: <irq>	loglevel=	All Kernel Messages with a loglevel smaller than the			console loglevel will be printed to the console. It can			also be changed with klogd or other programs. The			loglevels are defined as follows:			0 (KERN_EMERG)		system is unusable			1 (KERN_ALERT)		action must be taken immediately			2 (KERN_CRIT)		critical conditions			3 (KERN_ERR)		error conditions			4 (KERN_WARNING)	warning conditions			5 (KERN_NOTICE)		normal but significant condition			6 (KERN_INFO)		informational			7 (KERN_DEBUG)		debug-level messages	log_buf_len=n	Sets the size of the printk ring buffer, in bytes.			Format: { n | nk | nM }			n must be a power of two.  The default size			is set in the kernel config file.	logo.nologo	[FB] Disables display of the built-in Linux logo.			This may be used to provide more screen space for			kernel log messages and is useful when debugging			kernel boot problems.	lp=0		[LP]	Specify parallel ports to use, e.g,	lp=port[,port...]	lp=none,parport0 (lp0 not configured, lp1 uses	lp=reset		first parallel port). ‘lp=0‘ disables the	lp=auto			printer driver. ‘lp=reset‘ (which can be				specified in addition to the ports) causes				attached printers to be reset. Using				lp=port1,port2,... specifies the parallel ports				to associate lp devices with, starting with				lp0. A port specification may be ‘none‘ to skip				that lp device, or a parport name such as				‘parport0‘. Specifying ‘lp=auto‘ instead of a				port specification list means that device IDs				from each port should be examined, to see if				an IEEE 1284-compliant printer is attached; if				so, the driver will manage that printer.				See also header of drivers/char/lp.c.	lpj=n		[KNL]			Sets loops_per_jiffy to given constant, thus avoiding			time-consuming boot-time autodetection (up to 250 ms per			CPU). 0 enables autodetection (default). To determine			the correct value for your kernel, boot with normal			autodetection and see what value is printed. Note that			on SMP systems the preset will be applied to all CPUs,			which is likely to cause problems if your CPUs need			significantly divergent settings. An incorrect value			will cause delays in the kernel to be wrong, leading to			unpredictable I/O errors and other breakage. Although			unlikely, in the extreme case this might damage your			hardware.	ltpc=		[NET]			Format: <io>,<irq>,<dma>	mac5380=	[HW,SCSI] Format:			<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>	machvec=	[IA64] Force the use of a particular machine-vector			(machvec) in a generic kernel.			Example: machvec=hpzx1_swiotlb	machtype=	[Loongson] Share the same kernel image file between different			 yeeloong laptop.			Example: machtype=lemote-yeeloong-2f-7inch	max_addr=nn[KMG]	[KNL,BOOT,ia64] All physical memory greater			than or equal to this physical address is ignored.	maxcpus=	[SMP] Maximum number of processors that	an SMP kernel			should make use of.  maxcpus=n : n >= 0 limits the			kernel to using ‘n‘ processors.  n=0 is a special case,			it is equivalent to "nosmp", which also disables			the IO APIC.	max_loop=	[LOOP] Maximum number of loopback devices that can			be mounted			Format: <1-256>	max_luns=	[SCSI] Maximum number of LUNs to probe.			Should be between 1 and 2^32-1.	max_report_luns=			[SCSI] Maximum number of LUNs received.			Should be between 1 and 16384.	mcatest=	[IA-64]	mce		[X86-32] Machine Check Exception	mce=option	[X86-64] See Documentation/x86/x86_64/boot-options.txt	md=		[HW] RAID subsystems devices and level			See Documentation/md.txt.	mdacon=		[MDA]			Format: <first>,<last>			Specifies range of consoles to be captured by the MDA.	mem=nn[KMG]	[KNL,BOOT] Force usage of a specific amount of memory			Amount of memory to be used when the kernel is not able			to see the whole system memory or for test.			[X86-32] Use together with memmap= to avoid physical			address space collisions. Without memmap= PCI devices			could be placed at addresses belonging to unused RAM.	mem=nopentium	[BUGS=X86-32] Disable usage of 4MB pages for kernel			memory.	memchunk=nn[KMG]			[KNL,SH] Allow user to override the default size for			per-device physically contiguous DMA buffers.	memmap=exactmap	[KNL,X86] Enable setting of an exact			E820 memory map, as specified by the user.			Such memmap=exactmap lines can be constructed based on			BIOS output or other requirements. See the memmap=nn@ss			option description.	memmap=nn[KMG]@ss[KMG]			[KNL] Force usage of a specific region of memory			Region of memory to be used, from ss to ss+nn.	memmap=nn[KMG]#ss[KMG]			[KNL,ACPI] Mark specific memory as ACPI data.			Region of memory to be used, from ss to ss+nn.	memmap=nn[KMG]$ss[KMG]			[KNL,ACPI] Mark specific memory as reserved.			Region of memory to be used, from ss to ss+nn.			Example: Exclude memory from 0x18690000-0x1869ffff			         memmap=64K$0x18690000			         or			         memmap=0x10000$0x18690000	memory_corruption_check=0/1 [X86]			Some BIOSes seem to corrupt the first 64k of			memory when doing things like suspend/resume.			Setting this option will scan the memory			looking for corruption.  Enabling this will			both detect corruption and prevent the kernel			from using the memory being corrupted.			However, its intended as a diagnostic tool; if			repeatable BIOS-originated corruption always			affects the same memory, you can use memmap=			to prevent the kernel from using that memory.	memory_corruption_check_size=size [X86]			By default it checks for corruption in the low			64k, making this memory unavailable for normal			use.  Use this parameter to scan for			corruption in more or less memory.	memory_corruption_check_period=seconds [X86]			By default it checks for corruption every 60			seconds.  Use this parameter to check at some			other rate.  0 disables periodic checking.	memtest=	[KNL,X86] Enable memtest			Format: <integer>			default : 0 <disable>			Specifies the number of memtest passes to be			performed. Each pass selects another test			pattern from a given set of patterns. Memtest			fills the memory with this pattern, validates			memory contents and reserves bad memory			regions that are detected.	meye.*=		[HW] Set MotionEye Camera parameters			See Documentation/video4linux/meye.txt.	mfgpt_irq=	[IA-32] Specify the IRQ to use for the			Multi-Function General Purpose Timers on AMD Geode			platforms.	mfgptfix	[X86-32] Fix MFGPT timers on AMD Geode platforms when			the BIOS has incorrectly applied a workaround. TinyBIOS			version 0.98 is known to be affected, 0.99 fixes the			problem by letting the user disable the workaround.	mga=		[HW,DRM]	min_addr=nn[KMG]	[KNL,BOOT,ia64] All physical memory below this			physical address is ignored.	mini2440=	[ARM,HW,KNL]			Format:[0..2][b][c][t]			Default: "0tb"			MINI2440 configuration specification:			0 - The attached screen is the 3.5" TFT			1 - The attached screen is the 7" TFT			2 - The VGA Shield is attached (1024x768)			Leaving out the screen size parameter will not load			the TFT driver, and the framebuffer will be left			unconfigured.			b - Enable backlight. The TFT backlight pin will be			linked to the kernel VESA blanking code and a GPIO			LED. This parameter is not necessary when using the			VGA shield.			c - Enable the s3c camera interface.			t - Reserved for enabling touchscreen support. The			touchscreen support is not enabled in the mainstream			kernel as of 2.6.30, a preliminary port can be found			in the "bleeding edge" mini2440 support kernel at			http://repo.or.cz/w/linux-2.6/mini2440.git	mminit_loglevel=			[KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this			parameter allows control of the logging verbosity for			the additional memory initialisation checks. A value			of 0 disables mminit logging and a level of 4 will			log everything. Information is printed at KERN_DEBUG			so loglevel=8 may also need to be specified.	mousedev.tap_time=			[MOUSE] Maximum time between finger touching and			leaving touchpad surface for touch to be considered			a tap and be reported as a left button click (for			touchpads working in absolute mode only).			Format: <msecs>	mousedev.xres=	[MOUSE] Horizontal screen resolution, used for devices			reporting absolute coordinates, such as tablets	mousedev.yres=	[MOUSE] Vertical screen resolution, used for devices			reporting absolute coordinates, such as tablets	movablecore=nn[KMG]	[KNL,X86,IA-64,PPC] This parameter			is similar to kernelcore except it specifies the			amount of memory used for migratable allocations.			If both kernelcore and movablecore is specified,			then kernelcore will be at *least* the specified			value but may be more. If movablecore on its own			is specified, the administrator must be careful			that the amount of memory usable for all allocations			is not too small.	mpu401=		[HW,OSS]			Format: <io>,<irq>	MTD_Partition=	[MTD]			Format: <name>,<region-number>,<size>,<offset>	MTD_Region=	[MTD] Format:			<name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]	mtdparts=	[MTD]			See drivers/mtd/cmdlinepart.c.	onenand.bdry=	[HW,MTD] Flex-OneNAND Boundary Configuration			Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]			boundary - index of last SLC block on Flex-OneNAND.				   The remaining blocks are configured as MLC blocks.			lock	 - Configure if Flex-OneNAND boundary should be locked.				   Once locked, the boundary cannot be changed.				   1 indicates lock status, 0 indicates unlock status.	mtdset=		[ARM]			ARM/S3C2412 JIVE boot control			See arch/arm/mach-s3c2412/mach-jive.c	mtouchusb.raw_coordinates=			[HW] Make the MicroTouch USB driver use raw coordinates			(‘y‘, default) or cooked coordinates (‘n‘)	mtrr_chunk_size=nn[KMG] [X86]			used for mtrr cleanup. It is largest continuous chunk			that could hold holes aka. UC entries.	mtrr_gran_size=nn[KMG] [X86]			Used for mtrr cleanup. It is granularity of mtrr block.			Default is 1.			Large value could prevent small alignment from			using up MTRRs.	mtrr_spare_reg_nr=n [X86]			Format: <integer>			Range: 0,7 : spare reg number			Default : 1			Used for mtrr cleanup. It is spare mtrr entries number.			Set to 2 or more if your graphical card needs more.	n2=		[NET] SDL Inc. RISCom/N2 synchronous serial card	NCR_D700=	[HW,SCSI]			See header of drivers/scsi/NCR_D700.c.	ncr5380=	[HW,SCSI]	ncr53c400=	[HW,SCSI]	ncr53c400a=	[HW,SCSI]	ncr53c406a=	[HW,SCSI]	ncr53c8xx=	[HW,SCSI]	netdev=		[NET] Network devices parameters			Format: <irq>,<io>,<mem_start>,<mem_end>,<name>			Note that mem_start is often overloaded to mean			something different and driver-specific.			This usage is only documented in each driver source			file if at all.	nf_conntrack.acct=			[NETFILTER] Enable connection tracking flow accounting			0 to disable accounting			1 to enable accounting			Default value depends on CONFIG_NF_CT_ACCT that is			going to be removed in 2.6.29.	nfsaddrs=	[NFS]			See Documentation/filesystems/nfsroot.txt.	nfsroot=	[NFS] nfs root filesystem for disk-less boxes.			See Documentation/filesystems/nfsroot.txt.	nfs.callback_tcpport=			[NFS] set the TCP port on which the NFSv4 callback			channel should listen.	nfs.cache_getent=			[NFS] sets the pathname to the program which is used			to update the NFS client cache entries.	nfs.cache_getent_timeout=			[NFS] sets the timeout after which an attempt to			update a cache entry is deemed to have failed.	nfs.idmap_cache_timeout=			[NFS] set the maximum lifetime for idmapper cache			entries.	nfs.enable_ino64=			[NFS] enable 64-bit inode numbers.			If zero, the NFS client will fake up a 32-bit inode			number for the readdir() and stat() syscalls instead			of returning the full 64-bit number.			The default is to return 64-bit inode numbers.	nmi_debug=	[KNL,AVR32,SH] Specify one or more actions to take			when a NMI is triggered.			Format: [state][,regs][,debounce][,die]	nmi_watchdog=	[KNL,BUGS=X86] Debugging features for SMP kernels			Format: [panic,][num]			Valid num: 0,1,2			0 - turn nmi_watchdog off			1 - use the IO-APIC timer for the NMI watchdog			2 - use the local APIC for the NMI watchdog using			a performance counter. Note: This will use one			performance counter and the local APIC‘s performance			vector.			When panic is specified, panic when an NMI watchdog			timeout occurs.			This is useful when you use a panic=... timeout and			need the box quickly up again.			Instead of 1 and 2 it is possible to use the following			symbolic names: lapic and ioapic			Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic	netpoll.carrier_timeout=			[NET] Specifies amount of time (in seconds) that			netpoll should wait for a carrier. By default netpoll			waits 4 seconds.	no387		[BUGS=X86-32] Tells the kernel to use the 387 maths			emulation library even if a 387 maths coprocessor			is present.	no_console_suspend			[HW] Never suspend the console			Disable suspending of consoles during suspend and			hibernate operations.  Once disabled, debugging			messages can reach various consoles while the rest			of the system is being put to sleep (ie, while			debugging driver suspend/resume hooks).  This may			not work reliably with all consoles, but is known			to work with serial and VGA consoles.	noaliencache	[MM, NUMA, SLAB] Disables the allocation of alien			caches in the slab allocator.  Saves per-node memory,			but will impact performance.	noalign		[KNL,ARM]	noapic		[SMP,APIC] Tells the kernel to not make use of any			IOAPICs that may be present in the system.	nobats		[PPC] Do not use BATs for mapping kernel lowmem			on "Classic" PPC cores.	nocache		[ARM]	noclflush	[BUGS=X86] Don‘t use the CLFLUSH instruction	nodelayacct	[KNL] Disable per-task delay accounting	nodisconnect	[HW,SCSI,M68K] Disables SCSI disconnects.	nodsp		[SH] Disable hardware DSP at boot time.	noefi		[X86] Disable EFI runtime services support.	noexec		[IA-64]	noexec		[X86]			On X86-32 available only on PAE configured kernels.			noexec=on: enable non-executable mappings (default)			noexec=off: disable non-executable mappings	noexec32	[X86-64]			This affects only 32-bit executables.			noexec32=on: enable non-executable mappings (default)				read doesn‘t imply executable mappings			noexec32=off: disable non-executable mappings				read implies executable mappings	nofpu		[SH] Disable hardware FPU at boot time.	nofxsr		[BUGS=X86-32] Disables x86 floating point extended			register save and restore. The kernel will only save			legacy floating-point registers on task switch.	noxsave		[BUGS=X86] Disables x86 extended register state save			and restore using xsave. The kernel will fallback to			enabling legacy floating-point and sse state.	nohlt		[BUGS=ARM,SH] Tells the kernel that the sleep(SH) or			wfi(ARM) instruction doesn‘t work correctly and not to			use it. This is also useful when using JTAG debugger.	no-hlt		[BUGS=X86-32] Tells the kernel that the hlt			instruction doesn‘t work correctly and not to			use it.	no_file_caps	Tells the kernel not to honor file capabilities.  The			only way then for a file to be executed with privilege			is to be setuid root or executed by root.	nohalt		[IA-64] Tells the kernel not to use the power saving			function PAL_HALT_LIGHT when idle. This increases			power-consumption. On the positive side, it reduces			interrupt wake-up latency, which may improve performance			in certain environments such as networked servers or			real-time systems.	nohz=		[KNL] Boottime enable/disable dynamic ticks			Valid arguments: on, off			Default: on	noiotrap	[SH] Disables trapped I/O port accesses.	noirqdebug	[X86-32] Disables the code which attempts to detect and			disable unhandled interrupt sources.	no_timer_check	[X86,APIC] Disables the code which tests for			broken timer IRQ sources.	noisapnp	[ISAPNP] Disables ISA PnP code.	noinitrd	[RAM] Tells the kernel not to load any configured			initial RAM disk.	nointremap	[X86-64, Intel-IOMMU] Do not enable interrupt			remapping.	nointroute	[IA-64]	nojitter	[IA64] Disables jitter checking for ITC timers.	nolapic		[X86-32,APIC] Do not enable or use the local APIC.	nolapic_timer	[X86-32,APIC] Do not use the local APIC timer.	noltlbs		[PPC] Do not use large page/tlb entries for kernel			lowmem mapping on PPC40x.	nomca		[IA-64] Disable machine check abort handling	nomce		[X86-32] Machine Check Exception	nomfgpt		[X86-32] Disable Multi-Function General Purpose			Timer usage (for AMD Geode machines).	norandmaps	Don‘t use address space randomization.  Equivalent to			echo 0 > /proc/sys/kernel/randomize_va_space	noreplace-paravirt	[X86-32,PV_OPS] Don‘t patch paravirt_ops	noreplace-smp	[X86-32,SMP] Don‘t replace SMP instructions			with UP alternatives	noresidual	[PPC] Don‘t use residual data on PReP machines.	noresume	[SWSUSP] Disables resume and restores original swap			space.	no-scroll	[VGA] Disables scrollback.			This is required for the Braillex ib80-piezo Braille			reader made by F.H. Papenmeier (Germany).	nosbagart	[IA-64]	nosep		[BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.	nosmp		[SMP] Tells an SMP kernel to act as a UP kernel,			and disable the IO APIC.  legacy for "maxcpus=0".	nosoftlockup	[KNL] Disable the soft-lockup detector.	noswapaccount	[KNL] Disable accounting of swap in memory resource			controller. (See Documentation/cgroups/memory.txt)	nosync		[HW,M68K] Disables sync negotiation for all devices.	notsc		[BUGS=X86-32] Disable Time Stamp Counter	nousb		[USB] Disable the USB subsystem	nowb		[ARM]	nox2apic	[X86-64,APIC] Do not enable x2APIC mode.	nptcg=		[IA64] Override max number of concurrent global TLB			purges which is reported from either PAL_VM_SUMMARY or			SAL PALO.	nr_uarts=	[SERIAL] maximum number of UARTs to be registered.	numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.			one of [‘zone‘, ‘node‘, ‘default‘] can be specified			This can be set from sysctl after boot.			See Documentation/sysctl/vm.txt for details.	ohci1394_dma=early	[HW] enable debugging via the ohci1394 driver.			See Documentation/debugging-via-ohci1394.txt for more			info.	olpc_ec_timeout= [OLPC] ms delay when issuing EC commands			Rather than timing out after 20 ms if an EC			command is not properly ACKed, override the length			of the timeout.  We have interrupts disabled while			waiting for the ACK, so if this is set too high			interrupts *may* be lost!	opl3=		[HW,OSS]			Format: <io>	oprofile.timer=	[HW]			Use timer interrupt instead of performance counters	oprofile.cpu_type=	Force an oprofile cpu type			This might be useful if you have an older oprofile			userland or if you want common events.			Format: { arch_perfmon }			arch_perfmon: [X86] Force use of architectural				perfmon on Intel CPUs instead of the				CPU specific event set.	osst=		[HW,SCSI] SCSI Tape Driver			Format: <buffer_size>,<write_threshold>			See also Documentation/scsi/st.txt.	panic=		[KNL] Kernel behaviour on panic			Format: <timeout>	parkbd.port=	[HW] Parallel port number the keyboard adapter is			connected to, default is 0.			Format: <parport#>	parkbd.mode=	[HW] Parallel port keyboard adapter mode of operation,			0 for XT, 1 for AT (default is AT).			Format: <mode>	parport=	[HW,PPT] Specify parallel ports. 0 disables.			Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }			Use ‘auto‘ to force the driver to use any			IRQ/DMA settings detected (the default is to			ignore detected IRQ/DMA settings because of			possible conflicts). You can specify the base			address, IRQ, and DMA settings; IRQ and DMA			should be numbers, or ‘auto‘ (for using detected			settings on that particular port), or ‘nofifo‘			(to avoid using a FIFO even if it is detected).			Parallel ports are assigned in the order they			are specified on the command line, starting			with parport0.	parport_init_mode=	[HW,PPT]			Configure VIA parallel port to operate in			a specific mode. This is necessary on Pegasos			computer where firmware has no options for setting			up parallel port mode and sets it to spp.			Currently this function knows 686a and 8231 chips.			Format: [spp|ps2|epp|ecp|ecpepp]	pas2=		[HW,OSS] Format:			<io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>	pas16=		[HW,SCSI]			See header of drivers/scsi/pas16.c.	pause_on_oops=			Halt all CPUs after the first oops has been printed for			the specified number of seconds.  This is to be used if			your oopses keep scrolling off the screen.	pcbit=		[HW,ISDN]	pcd.		[PARIDE]			See header of drivers/block/paride/pcd.c.			See also Documentation/blockdev/paride.txt.	pci=option[,option...]	[PCI] various PCI subsystem options:		earlydump	[X86] dump PCI config space before the kernel			        changes anything		off		[X86] don‘t probe for the PCI bus		bios		[X86-32] force use of PCI BIOS, don‘t access				the hardware directly. Use this if your machine				has a non-standard PCI host bridge.		nobios		[X86-32] disallow use of PCI BIOS, only direct				hardware access methods are allowed. Use this				if you experience crashes upon bootup and you				suspect they are caused by the BIOS.		conf1		[X86] Force use of PCI Configuration				Mechanism 1.		conf2		[X86] Force use of PCI Configuration				Mechanism 2.		noaer		[PCIE] If the PCIEAER kernel config parameter is				enabled, this kernel boot option can be used to				disable the use of PCIE advanced error reporting.		nodomains	[PCI] Disable support for multiple PCI				root domains (aka PCI segments, in ACPI-speak).		nommconf	[X86] Disable use of MMCONFIG for PCI				Configuration		check_enable_amd_mmconf [X86] check for and enable				properly configured MMIO access to PCI				config space on AMD family 10h CPU		nomsi		[MSI] If the PCI_MSI kernel config parameter is				enabled, this kernel boot option can be used to				disable the use of MSI interrupts system-wide.		noioapicquirk	[APIC] Disable all boot interrupt quirks.				Safety option to keep boot IRQs enabled. This				should never be necessary.		ioapicreroute	[APIC] Enable rerouting of boot IRQs to the				primary IO-APIC for bridges that cannot disable				boot IRQs. This fixes a source of spurious IRQs				when the system masks IRQs.		noioapicreroute	[APIC] Disable workaround that uses the				boot IRQ equivalent of an IRQ that connects to				a chipset where boot IRQs cannot be disabled.				The opposite of ioapicreroute.		biosirq		[X86-32] Use PCI BIOS calls to get the interrupt				routing table. These calls are known to be buggy				on several machines and they hang the machine				when used, but on other computers it‘s the only				way to get the interrupt routing table. Try				this option if the kernel is unable to allocate				IRQs or discover secondary PCI buses on your				motherboard.		rom		[X86] Assign address space to expansion ROMs.				Use with caution as certain devices share				address decoders between ROMs and other				resources.		norom		[X86] Do not assign address space to				expansion ROMs that do not already have				BIOS assigned address ranges.		irqmask=0xMMMM	[X86] Set a bit mask of IRQs allowed to be				assigned automatically to PCI devices. You can				make the kernel exclude IRQs of your ISA cards				this way.		pirqaddr=0xAAAAA	[X86] Specify the physical address				of the PIRQ table (normally generated				by the BIOS) if it is outside the				F0000h-100000h range.		lastbus=N	[X86] Scan all buses thru bus #N. Can be				useful if the kernel is unable to find your				secondary buses and you want to tell it				explicitly which ones they are.		assign-busses	[X86] Always assign all PCI bus				numbers ourselves, overriding				whatever the firmware may have done.		usepirqmask	[X86] Honor the possible IRQ mask stored				in the BIOS $PIR table. This is needed on				some systems with broken BIOSes, notably				some HP Pavilion N5400 and Omnibook XE3				notebooks. This will have no effect if ACPI				IRQ routing is enabled.		noacpi		[X86] Do not use ACPI for IRQ routing				or for PCI scanning.		use_crs		[X86] Use _CRS for PCI resource				allocation.		routeirq	Do IRQ routing for all PCI devices.				This is normally done in pci_enable_device(),				so this option is a temporary workaround				for broken drivers that don‘t call it.		skip_isa_align	[X86] do not align io start addr, so can				handle more pci cards		firmware	[ARM] Do not re-enumerate the bus but instead				just use the configuration from the				bootloader. This is currently used on				IXP2000 systems where the bus has to be				configured a certain way for adjunct CPUs.		noearly		[X86] Don‘t do any early type 1 scanning.				This might help on some broken boards which				machine check when some devices‘ config space				is read. But various workarounds are disabled				and some IOMMU drivers will not work.		bfsort		Sort PCI devices into breadth-first order.				This sorting is done to get a device				order compatible with older (<= 2.4) kernels.		nobfsort	Don‘t sort PCI devices into breadth-first order.		cbiosize=nn[KMG]	The fixed amount of bus space which is				reserved for the CardBus bridge‘s IO window.				The default value is 256 bytes.		cbmemsize=nn[KMG]	The fixed amount of bus space which is				reserved for the CardBus bridge‘s memory				window. The default value is 64 megabytes.		resource_alignment=				Format:				[<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]				Specifies alignment and device to reassign				aligned memory resources.				If <order of align> is not specified,				PAGE_SIZE is used as alignment.				PCI-PCI bridge can be specified, if resource				windows need to be expanded.		ecrc=		Enable/disable PCIe ECRC (transaction layer				end-to-end CRC checking).				bios: Use BIOS/firmware settings. This is the				the default.				off: Turn ECRC off				on: Turn ECRC on.	pcie_aspm=	[PCIE] Forcibly enable or disable PCIe Active State Power			Management.		off	Disable ASPM.		force	Enable ASPM even on devices that claim not to support it.			WARNING: Forcing ASPM on may cause system lockups.	pcmv=		[HW,PCMCIA] BadgePAD 4	pd.		[PARIDE]			See Documentation/blockdev/paride.txt.	pdcchassis=	[PARISC,HW] Disable/Enable PDC Chassis Status codes at			boot time.			Format: { 0 | 1 }			See arch/parisc/kernel/pdc_chassis.c	percpu_alloc=	Select which percpu first chunk allocator to use.			Currently supported values are "embed" and "page".			Archs may support subset or none of the	selections.			See comments in mm/percpu.c for details on each			allocator.  This parameter is primarily	for debugging			and performance comparison.	pf.		[PARIDE]			See Documentation/blockdev/paride.txt.	pg.		[PARIDE]			See Documentation/blockdev/paride.txt.	pirq=		[SMP,APIC] Manual mp-table setup			See Documentation/x86/i386/IO-APIC.txt.	plip=		[PPT,NET] Parallel port network link			Format: { parport<nr> | timid | 0 }			See also Documentation/parport.txt.	pmtmr=		[X86] Manual setup of pmtmr I/O Port. 			Override pmtimer IOPort with a hex value.			e.g. pmtmr=0x508	pnp.debug	[PNP]			Enable PNP debug messages.  This depends on the			CONFIG_PNP_DEBUG_MESSAGES option.	pnpacpi=	[ACPI]			{ off }	pnpbios=	[ISAPNP]			{ on | off | curr | res | no-curr | no-res }	pnp_reserve_irq=			[ISAPNP] Exclude IRQs for the autoconfiguration	pnp_reserve_dma=			[ISAPNP] Exclude DMAs for the autoconfiguration	pnp_reserve_io=	[ISAPNP] Exclude I/O ports for the autoconfiguration			Ranges are in pairs (I/O port base and size).	pnp_reserve_mem=			[ISAPNP] Exclude memory regions for the			autoconfiguration.			Ranges are in pairs (memory base and size).	ports=		[IP_VS_FTP] IPVS ftp helper module			Default is 21.			Up to 8 (IP_VS_APP_MAX_PORTS) ports			may be specified.			Format: <port>,<port>....	print-fatal-signals=			[KNL] debug: print fatal signals			print-fatal-signals=1: print segfault info to			the kernel console.			default: off.	printk.time=	Show timing data prefixed to each printk message line			Format: <bool>  (1/Y/y=enable, 0/N/n=disable)	processor.max_cstate=	[HW,ACPI]			Limit processor to maximum C-state			max_cstate=9 overrides any DMI blacklist limit.	processor.nocst	[HW,ACPI]			Ignore the _CST method to determine C-states,			instead using the legacy FADT method	profile=	[KNL] Enable kernel profiling via /proc/profile			Format: [schedule,]<number>			Param: "schedule" - profile schedule points.			Param: <number> - step/bucket size as a power of 2 for				statistical time based profiling.			Param: "sleep" - profile D-state sleeping (millisecs).				Requires CONFIG_SCHEDSTATS			Param: "kvm" - profile VM exits.	prompt_ramdisk=	[RAM] List of RAM disks to prompt for floppy disk			before loading.			See Documentation/blockdev/ramdisk.txt.	psmouse.proto=	[HW,MOUSE] Highest PS2 mouse protocol extension to			probe for; one of (bare|imps|exps|lifebook|any).	psmouse.rate=	[HW,MOUSE] Set desired mouse report rate, in reports			per second.	psmouse.resetafter=	[HW,MOUSE]			Try to reset the device after so many bad packets			(0 = never).	psmouse.resolution=			[HW,MOUSE] Set desired mouse resolution, in dpi.	psmouse.smartscroll=			[HW,MOUSE] Controls Logitech smartscroll autorepeat.			0 = disabled, 1 = enabled (default).	pss=		[HW,OSS] Personal Sound System (ECHO ESC614)			Format:			<io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>	pt.		[PARIDE]			See Documentation/blockdev/paride.txt.	pty.legacy_count=			[KNL] Number of legacy pty‘s. Overwrites compiled-in			default number.	quiet		[KNL] Disable most log messages	r128=		[HW,DRM]	raid=		[HW,RAID]			See Documentation/md.txt.	ramdisk_blocksize=	[RAM]			See Documentation/blockdev/ramdisk.txt.	ramdisk_size=	[RAM] Sizes of RAM disks in kilobytes			See Documentation/blockdev/ramdisk.txt.	rcupdate.blimit=	[KNL,BOOT]			Set maximum number of finished RCU callbacks to process			in one batch.	rcupdate.qhimark=	[KNL,BOOT]			Set threshold of queued			RCU callbacks over which batch limiting is disabled.	rcupdate.qlowmark=	[KNL,BOOT]			Set threshold of queued RCU callbacks below which			batch limiting is re-enabled.	rdinit=		[KNL]			Format: <full_path>			Run specified binary instead of /init from the ramdisk,			used for early userspace startup. See initrd.	reboot=		[BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode			Format: <reboot_mode>[,<reboot_mode2>[,...]]			See arch/*/kernel/reboot.c or arch/*/kernel/process.c	relax_domain_level=			[KNL, SMP] Set scheduler‘s default relax_domain_level.			See Documentation/cgroups/cpusets.txt.	reserve=	[KNL,BUGS] Force the kernel to ignore some iomem area	reservetop=	[X86-32]			Format: nn[KMG]			Reserves a hole at the top of the kernel virtual			address space.	reset_devices	[KNL] Force drivers to reset the underlying device			during initialization.	resume=		[SWSUSP]			Specify the partition device for software suspend	resume_offset=	[SWSUSP]			Specify the offset from the beginning of the partition			given by "resume=" at which the swap header is located,			in <PAGE_SIZE> units (needed only for swap files).			See  Documentation/power/swsusp-and-swap-files.txt	retain_initrd	[RAM] Keep initrd memory after extraction	rhash_entries=	[KNL,NET]			Set number of hash buckets for route cache	riscom8=	[HW,SERIAL]			Format: <io_board1>[,<io_board2>[,...<io_boardN>]]	ro		[KNL] Mount root device read-only on boot	root=		[KNL] Root filesystem	rootdelay=	[KNL] Delay (in seconds) to pause before attempting to			mount the root filesystem	rootflags=	[KNL] Set root filesystem mount option string	rootfstype=	[KNL] Set root filesystem type	rootwait	[KNL] Wait (indefinitely) for root device to show up.			Useful for devices that are detected asynchronously			(e.g. USB and MMC devices).	root_plug.vendor_id=			[ROOTPLUG] Override the default vendor ID	root_plug.product_id=			[ROOTPLUG] Override the default product ID	root_plug.debug=			[ROOTPLUG] Enable debugging output	rw		[KNL] Mount root device read-write on boot	S		[KNL] Run init in single mode	sa1100ir	[NET]			See drivers/net/irda/sa1100_ir.c.	sbni=		[NET] Granch SBNI12 leased line adapter	sc1200wdt=	[HW,WDT] SC1200 WDT (watchdog) driver			Format: <io>[,<timeout>[,<isapnp>]]	scsi_debug_*=	[SCSI]			See drivers/scsi/scsi_debug.c.	scsi_default_dev_flags=			[SCSI] SCSI default device flags			Format: <integer>	scsi_dev_flags=	[SCSI] Black/white list entry for vendor and model			Format: <vendor>:<model>:<flags>			(flags are integer value)	scsi_logging_level=	[SCSI] a bit mask of logging levels			See drivers/scsi/scsi_logging.h for bits.  Also			settable via sysctl at dev.scsi.logging_level			(/proc/sys/dev/scsi/logging_level).			There is also a nice ‘scsi_logging_level‘ script in the			S390-tools package, available for download at			http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html	scsi_mod.scan=	[SCSI] sync (default) scans SCSI busses as they are			discovered.  async scans them in kernel threads,			allowing boot to proceed.  none ignores them, expecting			user space to do the scan.	security=	[SECURITY] Choose a security module to enable at boot.			If this boot parameter is not specified, only the first			security module asking for security registration will be			loaded. An invalid security module name will be treated			as if no module has been chosen.	selinux=	[SELINUX] Disable or enable SELinux at boot time.			Format: { "0" | "1" }			See security/selinux/Kconfig help text.			0 -- disable.			1 -- enable.			Default value is set via kernel config option.			If enabled at boot time, /selinux/disable can be used			later to disable prior to initial policy load.	serialnumber	[BUGS=X86-32]	shapers=	[NET]			Maximal number of shapers.	show_msr=	[x86] show boot-time MSR settings			Format: { <integer> }			Show boot-time (BIOS-initialized) MSR settings.			The parameter means the number of CPUs to show,			for example 1 means boot CPU only.	sim710=		[SCSI,HW]			See header of drivers/scsi/sim710.c.	simeth=		[IA-64]	simscsi=	slram=		[HW,MTD]	slub_debug[=options[,slabs]]	[MM, SLUB]			Enabling slub_debug allows one to determine the			culprit if slab objects become corrupted. Enabling			slub_debug can create guard zones around objects and			may poison objects when not in use. Also tracks the			last alloc / free. For more information see			Documentation/vm/slub.txt.	slub_max_order= [MM, SLUB]			Determines the maximum allowed order for slabs.			A high setting may cause OOMs due to memory			fragmentation. For more information see			Documentation/vm/slub.txt.	slub_min_objects=	[MM, SLUB]			The minimum number of objects per slab. SLUB will			increase the slab order up to slub_max_order to			generate a sufficiently large slab able to contain			the number of objects indicated. The higher the number			of objects the smaller the overhead of tracking slabs			and the less frequently locks need to be acquired.			For more information see Documentation/vm/slub.txt.	slub_min_order=	[MM, SLUB]			Determines the mininum page order for slabs. Must be			lower than slub_max_order.			For more information see Documentation/vm/slub.txt.	slub_nomerge	[MM, SLUB]			Disable merging of slabs with similar size. May be			necessary if there is some reason to distinguish			allocs to different slabs. Debug options disable			merging on their own.			For more information see Documentation/vm/slub.txt.	smart2=		[HW]			Format: <io1>[,<io2>[,...,<io8>]]	smp-alt-once	[X86-32,SMP] On a hotplug CPU system, only			attempt to substitute SMP alternatives once at boot.	smsc-ircc2.nopnp	[HW] Don‘t use PNP to discover SMC devices	smsc-ircc2.ircc_cfg=	[HW] Device configuration I/O port	smsc-ircc2.ircc_sir=	[HW] SIR base I/O port	smsc-ircc2.ircc_fir=	[HW] FIR base I/O port	smsc-ircc2.ircc_irq=	[HW] IRQ line	smsc-ircc2.ircc_dma=	[HW] DMA channel	smsc-ircc2.ircc_transceiver= [HW] Transceiver type:				0: Toshiba Satellite 1800 (GP data pin select)				1: Fast pin select (default)				2: ATC IRMode	snd-ad1816a=	[HW,ALSA]	snd-ad1848=	[HW,ALSA]	snd-ali5451=	[HW,ALSA]	snd-als100=	[HW,ALSA]	snd-als4000=	[HW,ALSA]	snd-azt2320=	[HW,ALSA]	snd-cmi8330=	[HW,ALSA]	snd-cmipci=	[HW,ALSA]	snd-cs4231=	[HW,ALSA]	snd-cs4232=	[HW,ALSA]	snd-cs4236=	[HW,ALSA]	snd-cs4281=	[HW,ALSA]	snd-cs46xx=	[HW,ALSA]	snd-dt019x=	[HW,ALSA]	snd-dummy=	[HW,ALSA]	snd-emu10k1=	[HW,ALSA]	snd-ens1370=	[HW,ALSA]	snd-ens1371=	[HW,ALSA]	snd-es968=	[HW,ALSA]	snd-es1688=	[HW,ALSA]	snd-es18xx=	[HW,ALSA]	snd-es1938=	[HW,ALSA]	snd-es1968=	[HW,ALSA]	snd-fm801=	[HW,ALSA]	snd-gusclassic=	[HW,ALSA]	snd-gusextreme=	[HW,ALSA]	snd-gusmax=	[HW,ALSA]	snd-hdsp=	[HW,ALSA]	snd-ice1712=	[HW,ALSA]	snd-intel8x0=	[HW,ALSA]	snd-interwave=	[HW,ALSA]	snd-interwave-stb=			[HW,ALSA]	snd-korg1212=	[HW,ALSA]	snd-maestro3=	[HW,ALSA]	snd-mpu401=	[HW,ALSA]	snd-mtpav=	[HW,ALSA]	snd-nm256=	[HW,ALSA]	snd-opl3sa2=	[HW,ALSA]	snd-opti92x-ad1848=			[HW,ALSA]	snd-opti92x-cs4231=			[HW,ALSA]	snd-opti93x=	[HW,ALSA]	snd-pmac=	[HW,ALSA]	snd-rme32=	[HW,ALSA]	snd-rme96=	[HW,ALSA]	snd-rme9652=	[HW,ALSA]	snd-sb8=	[HW,ALSA]	snd-sb16=	[HW,ALSA]	snd-sbawe=	[HW,ALSA]	snd-serial=	[HW,ALSA]	snd-sgalaxy=	[HW,ALSA]	snd-sonicvibes=	[HW,ALSA]	snd-sun-amd7930=			[HW,ALSA]	snd-sun-cs4231=	[HW,ALSA]	snd-trident=	[HW,ALSA]	snd-usb-audio=	[HW,ALSA,USB]	snd-via82xx=	[HW,ALSA]	snd-virmidi=	[HW,ALSA]	snd-wavefront=	[HW,ALSA]	snd-ymfpci=	[HW,ALSA]	softlockup_panic=			[KNL] Should the soft-lockup detector generate panics.	sonypi.*=	[HW] Sony Programmable I/O Control Device driver			See Documentation/sonypi.txt	specialix=	[HW,SERIAL] Specialix multi-serial port adapter			See Documentation/serial/specialix.txt.	spia_io_base=	[HW,MTD]	spia_fio_base=	spia_pedr=	spia_peddr=	sscape=		[HW,OSS]			Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>	st=		[HW,SCSI] SCSI tape parameters (buffers, etc.)			See Documentation/scsi/st.txt.	stacktrace	[FTRACE]			Enabled the stack tracer on boot up.	sti=		[PARISC,HW]			Format: <num>			Set the STI (builtin display/keyboard on the HP-PARISC			machines) console (graphic card) which should be used			as the initial boot-console.			See also comment in drivers/video/console/sticore.c.	sti_font=	[HW]			See comment in drivers/video/console/sticore.c.	stifb=		[HW]			Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]	sunrpc.min_resvport=	sunrpc.max_resvport=			[NFS,SUNRPC]			SunRPC servers often require that client requests			originate from a privileged port (i.e. a port in the			range 0 < portnr < 1024).			An administrator who wishes to reserve some of these			ports for other uses may adjust the range that the			kernel‘s sunrpc client considers to be privileged			using these two parameters to set the minimum and			maximum port values.	sunrpc.pool_mode=			[NFS]			Control how the NFS server code allocates CPUs to			service thread pools.  Depending on how many NICs			you have and where their interrupts are bound, this			option will affect which CPUs will do NFS serving.			Note: this parameter cannot be changed while the			NFS server is running.			auto	    the server chooses an appropriate mode				    automatically using heuristics			global	    a single global pool contains all CPUs			percpu	    one pool for each CPU			pernode	    one pool for each NUMA node (equivalent				    to global on non-NUMA machines)	sunrpc.tcp_slot_table_entries=	sunrpc.udp_slot_table_entries=			[NFS,SUNRPC]			Sets the upper limit on the number of simultaneous			RPC calls that can be sent from the client to a			server. Increasing these values may allow you to			improve throughput, but will also increase the			amount of memory reserved for use by the client.	swiotlb=	[IA-64] Number of I/O TLB slabs	switches=	[HW,M68k]	sym53c416=	[HW,SCSI]			See header of drivers/scsi/sym53c416.c.	sysrq_always_enabled			[KNL]			Ignore sysrq setting - this boot parameter will			neutralize any effect of /proc/sys/kernel/sysrq.			Useful for debugging.	t128=		[HW,SCSI]			See header of drivers/scsi/t128.c.	tdfx=		[HW,DRM]	test_suspend=	[SUSPEND]			Specify "mem" (for Suspend-to-RAM) or "standby" (for			standby suspend) as the system sleep state to briefly			enter during system startup.  The system is woken from			this state using a wakeup-capable RTC alarm.	thash_entries=	[KNL,NET]			Set number of hash buckets for TCP connection	thermal.act=	[HW,ACPI]			-1: disable all active trip points in all thermal zones			<degrees C>: override all lowest active trip points	thermal.crt=	[HW,ACPI]			-1: disable all critical trip points in all thermal zones			<degrees C>: override all critical trip points	thermal.nocrt=	[HW,ACPI]			Set to disable actions on ACPI thermal zone			critical and hot trip points.	thermal.off=	[HW,ACPI]			1: disable ACPI thermal control	thermal.psv=	[HW,ACPI]			-1: disable all passive trip points			<degrees C>: override all passive trip points to this			value	thermal.tzp=	[HW,ACPI]			Specify global default ACPI thermal zone polling rate			<deci-seconds>: poll all this frequency			0: no polling (default)	tmscsim=	[HW,SCSI]			See comment before function dc390_setup() in			drivers/scsi/tmscsim.c.	topology=	[S390]			Format: {off | on}			Specify if the kernel should make use of the cpu			topology informations if the hardware supports these.			The scheduler will make use of these informations and			e.g. base its process migration decisions on it.			Default is off.	tp720=		[HW,PS2]	trace_buf_size=nn[KMG]			[FTRACE] will set tracing buffer size.	trace_event=[event-list]			[FTRACE] Set and start specified trace events in order			to facilitate early boot debugging.			See also Documentation/trace/events.txt	trix=		[HW,OSS] MediaTrix AudioTrix Pro			Format:			<io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>	tsc=		Disable clocksource-must-verify flag for TSC.			Format: <string>			[x86] reliable: mark tsc clocksource as reliable, this			disables clocksource verification at runtime.			Used to enable high-resolution timer mode on older			hardware, and in virtualized environment.	turbografx.map[2|3]=	[HW,JOY]			TurboGraFX parallel port interface			Format:			<port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>			See also Documentation/input/joystick-parport.txt	u14-34f=	[HW,SCSI] UltraStor 14F/34F SCSI host adapter			See header of drivers/scsi/u14-34f.c.	uart401=	[HW,OSS]			Format: <io>,<irq>	uart6850=	[HW,OSS]			Format: <io>,<irq>	uhci-hcd.ignore_oc=			[USB] Ignore overcurrent events (default N).			Some badly-designed motherboards generate lots of			bogus events, for ports that aren‘t wired to			anything.  Set this parameter to avoid log spamming.			Note that genuine overcurrent events won‘t be			reported either.	unknown_nmi_panic			[X86]			Set unknown_nmi_panic=1 early on boot.	usbcore.autosuspend=			[USB] The autosuspend time delay (in seconds) used			for newly-detected USB devices (default 2).  This			is the time required before an idle device will be			autosuspended.  Devices for which the delay is set			to a negative value won‘t be autosuspended at all.	usbcore.usbfs_snoop=			[USB] Set to log all usbfs traffic (default 0 = off).	usbcore.blinkenlights=			[USB] Set to cycle leds on hubs (default 0 = off).	usbcore.old_scheme_first=			[USB] Start with the old device initialization			scheme (default 0 = off).	usbcore.use_both_schemes=			[USB] Try the other device initialization scheme			if the first one fails (default 1 = enabled).	usbcore.initial_descriptor_timeout=			[USB] Specifies timeout for the initial 64-byte                        USB_REQ_GET_DESCRIPTOR request in milliseconds			(default 5000 = 5.0 seconds).	usbhid.mousepoll=			[USBHID] The interval which mice are to be polled at.	usb-storage.delay_use=			[UMS] The delay in seconds before a new device is			scanned for Logical Units (default 5).	usb-storage.quirks=			[UMS] A list of quirks entries to supplement or			override the built-in unusual_devs list.  List			entries are separated by commas.  Each entry has			the form VID:PID:Flags where VID and PID are Vendor			and Product ID values (4-digit hex numbers) and			Flags is a set of characters, each corresponding			to a common usb-storage quirk flag as follows:				a = SANE_SENSE (collect more than 18 bytes					of sense data);				c = FIX_CAPACITY (decrease the reported					device capacity by one sector);				h = CAPACITY_HEURISTICS (decrease the					reported device capacity by one					sector if the number is odd);				i = IGNORE_DEVICE (don‘t bind to this					device);				l = NOT_LOCKABLE (don‘t try to lock and					unlock ejectable media);				m = MAX_SECTORS_64 (don‘t transfer more					than 64 sectors = 32 KB at a time);				o = CAPACITY_OK (accept the capacity					reported by the device);				r = IGNORE_RESIDUE (the device reports					bogus residue values);				s = SINGLE_LUN (the device has only one					Logical Unit);				w = NO_WP_DETECT (don‘t test whether the					medium is write-protected).			Example: quirks=0419:aaf5:rl,0421:0433:rc	vdso=		[X86,SH]			vdso=2: enable compat VDSO (default with COMPAT_VDSO)			vdso=1: enable VDSO (default)			vdso=0: disable VDSO mapping	vdso32=		[X86]			vdso32=2: enable compat VDSO (default with COMPAT_VDSO)			vdso32=1: enable 32-bit VDSO (default)			vdso32=0: disable 32-bit VDSO mapping	vector=		[IA-64,SMP]			vector=percpu: enable percpu vector domain	video=		[FB] Frame buffer configuration			See Documentation/fb/modedb.txt.	vga=		[BOOT,X86-32] Select a particular video mode			See Documentation/x86/boot.txt and			Documentation/svga.txt.			Use vga=ask for menu.			This is actually a boot loader parameter; the value is			passed to the kernel using a special protocol.	vmalloc=nn[KMG]	[KNL,BOOT] Forces the vmalloc area to have an exact			size of <nn>. This can be used to increase the			minimum size (128MB on x86). It can also be used to			decrease the size and leave more room for directly			mapped kernel RAM.	vmhalt=		[KNL,S390] Perform z/VM CP command after system halt.			Format: <command>	vmpanic=	[KNL,S390] Perform z/VM CP command after kernel panic.			Format: <command>	vmpoff=		[KNL,S390] Perform z/VM CP command after power off.			Format: <command>	vt.default_blu=	[VT]			Format: <blue0>,<blue1>,<blue2>,...,<blue15>			Change the default blue palette of the console.			This is a 16-member array composed of values			ranging from 0-255.	vt.default_grn=	[VT]			Format: <green0>,<green1>,<green2>,...,<green15>			Change the default green palette of the console.			This is a 16-member array composed of values			ranging from 0-255.	vt.default_red=	[VT]			Format: <red0>,<red1>,<red2>,...,<red15>			Change the default red palette of the console.			This is a 16-member array composed of values			ranging from 0-255.	vt.default_utf8=			[VT]			Format=<0|1>			Set system-wide default UTF-8 mode for all tty‘s.			Default is 1, i.e. UTF-8 mode is enabled for all			newly opened terminals.	waveartist=	[HW,OSS]			Format: <io>,<irq>,<dma>,<dma2>	wd33c93=	[HW,SCSI]			See header of drivers/scsi/wd33c93.c.	wd7000=		[HW,SCSI]			See header of drivers/scsi/wd7000.c.	wdt=		[WDT] Watchdog			See Documentation/watchdog/wdt.txt.	x2apic_phys	[X86-64,APIC] Use x2apic physical mode instead of			default x2apic cluster mode on platforms			supporting x2apic.	xd=		[HW,XT] Original XT pre-IDE (RLL encoded) disks.	xd_geo=		See header of drivers/block/xd.c.	xirc2ps_cs=	[NET,PCMCIA]			Format:			<irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]______________________________________________________________________TODO:	Add documentation for ALSA options.	Add more DRM drivers.
----------------------------------------------------------------------------------------------------------------------------------------------

作者：北南南北
来自：LinuxSir.Org
摘要： GRUB是多系统引导管理器，简单的说既能引导Linux，同时也能引导Windows；从LinuxSir.Org 讨论区近四年的观察来看，大多初学者并不能在短时间内掌握GRUB的用法，为了解决初学者在最短时间内掌握GRUB，重写GRUB入门文档还是有必要的；
本文重点介绍了GRUB的menu.lst的写法，另外通过GRUB命令行引导系统也做了详述；这些无论是对Windows版本的WINGRUB还是Linux版本的GRUB都是适用的；
目录索引
一、什么是多重操作系统引导管理器，什么是GRUB；
1、什么是多重操作系统引导管理器及工作原理；
2、什么是GRUB；为什么我要选择GRUB； 

1）什么是GRUB；
2）“GRUB太不好用”──对GRUB的认识的误区；
3）为什么要选择GRUB； 


二、GRUB软件包版本选择和安装；
1、Linux版本的GRUB及Windows版本的GRUB的说明；
2、GRUB的Windows版本WINGRUB；
3、GRUB的Linux版本软件包的安装； 

三、在Linux中，GRUB的配置中的安装和写入硬盘的MBR；
1、在Linux中，GRUB配置过程中的安装grub-install；
2、设定GRUB的/boot分区并写入MBR； 

四、GRUB的配置文件的menu.lst的写法；
1、menu.lst的写法之一； 

1）在menu.lst中 ，通过 root (hd[0-n],y)来指定/boot 所在的分区；
2）在menu.lst中，kernel 命令行的写法；
3）initrd 命令行的写法；
4）menu.lst第一种写法的总结和实践； 

1］用fdisk -l ；df -lh ；more /etc/fstab来确认分区情况；
2］查看内核vmlinuz的和initrd文件名的全称；
3］开始写menu.lst ； 


2、menu.lst的写法之二，精简型；
1）第一种情况：/boot和Linux的/根分区在同一个分区；
2）第二种情况：/boot独立一个分区，和Linux的根分区不位于同一分区； 


五、通过GRUB命令行来启动Linux操作系统；
1、为什么需要学习GRUB的命令行；
2、用命令行来引导Linux操作系统的步骤； 

1）进入GRUB的命令行模式 grub>
2）获取帮助GRUB的 help 
3）cat的用法；
4）root (hd[0-n,y) 指令来指定/boot所在的分区；
5）kernel 指令，用来指定Linux的内核，及/所在的分区；
6）initrd 命令行来指定initrd文件；
7）boot 引导系统；
8）引导Linux系统实例全程回放； 


六、通过GRUB引导Windows操作系统；
1、通过编辑 menu.lst 来引导Windows 系统；
2、通过GRUB指令来引导Windows ； 

七、GRUB丢失或损坏的应对策略；
1、由于重新安装Windows或其它未知原因而导致GRUB的丢失；
2、如果出现GRUB提示符，而不出现GRUB的菜单，如何引导系统； 

八、关于GRUB的未尽事宜；
九、关于本文；
十、参考文档；
十一、相关文档；

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正文
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一、什么是多重操作系统引导管理器，什么是GRUB；


1、什么是多重操作系统引导管理器及工作原理；

系统启动引导管理器，是在计算机启动后运行的第一个程序，他是用来负责加载、传输控制到操作系统的内核，一旦把内核挂载，系统引导管理器的任务就算完成退出，系统引导的其它部份，比如系统的初始化及启动过程则完全由内核来控制完成；

Briefly, boot loader is the first software program that runs when a computer starts. It is responsible for loading and transferring control to the operating system kernel software (such as the Hurd or the Linux). The kernel, in turn, initializes the rest of the operating system (e.g. GNU).

在X86 架构的机器中，Linux、BSD 或其它Unix类的操作系统中GRUB、LILO 是大家最为常用，应该说是主流；
Windows 也有类似的工具NTLOADER；比如我们在机器中安装了Windows 98后，我们再安装一个Windows XP ，在机器启动的会有一个菜单让我们选择进入是进入Windows 98 还是进入Windows XP。NTLOADER就是一个多系统启动引导管理器，NTLOADER 同样也能引导Linux，只是极为麻烦罢了；
在Powerpc 架构的机器中，如果安装了Linux的Powerpc 版本，大多是用yaboot 多重引导管理器，比如Apple机目前用的是IBM Powerpc处理器，所以在如果想在Apple机上，安装Macos 和Linux Powerpc 版本，大多是用yaboot来引导多个操作系统；
因为目前X86架构的机器仍是主流， 所以目前GRUB和LILO 仍然是我们最常用的多重操作系统引导管理器；

2、什么是GRUB；为什么我要选择GRUB；


1）什么是GRUB；

GNU GRUB 是一个多重操作系统启动管理器。GNU GRUB 是由GRUB（GRand Unified Bootloader） 派生而来。GRUB 最初由Erich Stefan Boleyn 设计和应用；

GNU GRUB is a Multiboot boot loader. It was derived from GRUB, GRand Unified Bootloader, which was originally designed and implemented by Erich Stefan Boleyn.


2）“GRUB太不好用”──对GRUB的认识的误区；

GRUB真的不好用吗？不是的，通过LinuxSir.Org 社区近四年来的运行，我发现了大多新手弟兄还是不太了解GRUB；当然这也有中文Linux社区的责任，虽然也有GRUB的中文译本，初学Linux的弟兄可能有点看不懂；
我 们欣喜的看到LinuxSir.Org 社区的好多弟兄都曾经或正在写GRUB实践文档，也有的弟兄也总结了GRUB的一些基础知识，比如 probing兄弟的 《GRUB 学习笔记》；由于每个人的写文档时风格不同，可能同一份文档不同的人来写就有不同的风格；所以今天也抖胆也一篇入门级的教程，由于北南不会写高级教程，所 以还得请高手弟兄指教，先谢过；

3）为什么要选择GRUB；

基于在X86架构的CPU而开发操作系统，系统引导管理器不仅仅有GRUB ，而且也有LILO，但对于多重系统引导管理器，你只能选择其一而用；不能两个同时使用；
目前这两个多重系统引导管理器是大家最常用的，也是主流Linux发行版而采用的；有的弟兄喜欢GRUB，比如我个人，有的弟兄喜欢LILO ，比如etony兄（谁是etony，请参见 http://debian.linuxsir.org ）；
主流发行版 Fedora、Redhat、Centos等基于RPM包的系统，在最新版本中都默认GRUB引导；Slackware 目前仍采用LILO；而Debian发行版目前最新的版本也是采用GRUB；
从目前看来，GRUB有逐渐取代LILO之势，GRUB 2.0正在开发之中；所以我们有理由用GRUB，我也有理由写GRUB使用教程；

二、GRUB软件包版本选择和安装；


1、GRUB的版本选择，Linux版本的GRUB及Windows版本的GRUB的说明；

GRUB不但有Linux版本，也有Windows版本；现我们一一介绍；
如 前面所说，目前在在Unix类的操作系统中，大多是都有GRUB；GRUB几乎能引导所有X86架构的操作系统；功能之强，使用简单是GRUB最大的卖 点；由于Windows 操作系统的先入为主的优势，使得大家对Windows的NTLOADER了解的比较多，而对开源社区的GRUB显得有点寞生，由此而带来使用上的“心理恐 惧”；究其初学者对GRUB“恐惧”的主要原因还是对GRUB没有太多的了解和深入；无论是WINGRUB还是Linux版本的GRUB，最方便的还是对 GRUB命令行的操作；一谈到命令行（Command）的操作，可能初学者对此恐惧；其实没有什么难的，象北南这样低级的写手，还能操作得起来，您也应该 能行；

2、GRUB的Windows版本WINGRUB；

请参考：《以WINGRUB 引导安装Fedora 4.0 为例，详述用WINGRUB来引导Linux的安装》

3、GRUB的Linux版本软件包的安装；

其实对于Linux的GRUB，几乎所有的Linux主流发行版都有打包，如果您安装了Linux，并且在开机后出现GRUB字样的，证明您已经安装了GRUB；而无需再次安装；Linux的GRUB软件包安装部份并不是本文的重点；
如果您的Linux系统没有安装GRUB，或者采用的是LILO，而您想用GRUB，可以用系统安装盘自带GRUB软件包来安装，或者到相关发行版本的软件仓库下载后安装；
GRUB 的Linux版本目前在各大发行版中都有打包；比如Fedora/Redhat/Centos/Mandrive/Mandriva/SuSE等以RPM包管理机制的系统，可以通过如下的命令来安装；
请参考《Fedora / Redhat 软件包管理指南》
[root@localhost ~]# rpm -ivh grub*.rpm

如果是Slackware 您可以用如下的办法来安装；
[root@localhost ~]# installpkg grub*.tgz

其它的发行版本请用其自己特色的软件包管理工具来安装；
当然您也可以通过源码包，在任何Linux的发行版上安装；至于源码包的安装方法；
请参考：《如何编译安装源码包软件》
[root@localhost ~]#tar zxvf grub*.tar.gz
[root@localhost ~]#cd grub-xxx
[root@localhost ~]#./configure;make;make install

确认您是否成功安装了GRUB，您可以测试是否有如下两个命令；
[root@localhost ~]# grub
[root@localhost ~]# grub-install

如果您不能找到这两个命令，可能您的可执行程序的路径没有设置；
请参考：《设置可执行程序路径》，当然您可以用绝对路径；比如下面的；
[root@localhost ~]# /usr/sbin/grub
[root@localhost ~]# /usr/sbin/grub-install

如果您还是找不到GRUB软件包安装在哪了；您可以用下面的命令来解决和查找；
[root@localhost ~]# updatedb 注：这个要花很长时间；是索引slocate 的库，然后再通过locate来查找；
[root@localhost ~]# locate grub 

比如找到的是有类似如下的；
[root@localhost ~]# locate grub 
/sbin/grub-md5-crypt
/sbin/grub
/sbin/grub-install
/sbin/grub-terminfo

在一般情况下，在路径中带有bin或sbin中字样的，这些路径下都是可执行程序；sbin 是超级权限用户才能使用的管理命令；要使用这些命令一般的情况下得切换到root用户下才能使用；比如
[beinan@localhost ~]$ su - 注：切换到root用户，并且切换到其家目录；
Password:
[root@localhost ~]#/sbin/grub 注：用绝对路径来运行grub命令；


三、在Linux中，GRUB的配置中的安装和写入硬盘的MBR；


1、在Linux中，GRUB配置过程中的安装grub-install；

grub-install 命令有何用呢？其实就是把我们前面已经安装的软件包中的一些文件复制到 /boot/grub中；对于新安装GRUB软件包后，也是一个必经的过程；我们前面所说的GRUB软件包的安装；而现在我们说的是GRUB配置的过程中 的安装；虽然在洋文中都是install ，但表达的意思是不一样的；
我们首先要运行 fdisk -l 来确认到底是硬盘的标识；
这个过程主要是确认硬盘的标识是哪个调备，到底是/dev/hda还是/dev/hdb 还是其它的；
[root@localhost ~]# fdisk -l

Disk /dev/hda: 80.0 GB, 80026361856 bytes
255 heads, 63 sectors/track, 9729 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System
/dev/hda1 * 1 970 7791493+ 7 HPFS/NTFS
/dev/hda2 971 9729 70356667+ 5 Extended
/dev/hda5 971 2915 15623181 b W95 FAT32
/dev/hda6 2916 4131 9767488+ 83 Linux
/dev/hda7 4132 5590 11719386 83 Linux
/dev/hda8 5591 6806 9767488+ 83 Linux
/dev/hda9 6807 9657 22900626 83 Linux
/dev/hda10 9658 9729 578308+ 82 Linux swap / Solaris

如果通过fdisk -l 出现有/dev/hda字样的，我们就要用下面的命令来安装；
[root@localhost ~]# grub-install /dev/hda
Installation finished. No error reported.
This is the contents of the device map /boot/grub/device.map.
Check if this is correct or not. If any of the lines is incorrect,
fix it and re-run the script `grub-install‘.

(fd0) /dev/fd0
(hd0) /dev/hda

如果是您fdisk -l 出现的有/dev/hdb呢，那就如下运行；
[root@localhost ~]# grub-install /dev/hdb

如果既有/dev/hda和/dev/hdb 就安装到/dev/hda中；
[root@localhost ~]# grub-install /dev/hda

值得注意的是如果您有一个/boot分区，应该用如下的办法来安装； 
[root@localhost ~]#grub-install --root-directory=/boot /dev/hda

[root@localhost ~]#grub-install --root-directory=/boot /dev/hdb

注解：具体是/dev/hda还是/dev/hdb，请以fdisk -l 为准；如果两个都有，就看您把/boot分区是放在第一块硬盘还是第二块硬盘上了，以实际情况为准；

2、设定GRUB的/boot分区并写入MBR；；

在Linux中，GRUB软件包的安装，及在配置过程中安装grub到 /boot中还是不够的， 还要把GRUB，写入MBR才行；有时我们重新安装了Windows，Windows会把MBR 重写，这样GRUB就消失了；如果您出现这样的情况，就要进行这个过程；
[root@localhost ~]# grub

会出现grub>提示符，这是grub命令行模式 ，如果能在开机中出现提示符，没有引导不起来的系统，除非您的系统破坏的极为严重。如果仅仅是GRUB被破坏了，GRUB命令行是能让操作系统引导起来的；
接着看例子，我们要找到 /boot/grub/stage1的，在grub>后面输入；
grub> find /boot/grub/stage1
(hd0,6) 
(fd0) 注：这个是软驱；现在很少用软驱了，如果您有这方面的需要，自己看GRUB的DOC吧；

注解：
(hd0,6) 这是/boot所在的分区；不要误解为是Linux 的/所在的分区，这是值得注意的；
(fd0) 注：这个是软驱；现在很少用软驱了，如果您有这方面的需要，自己看GRUB的DOC吧；
grub>root (hd0,6) 注：这是/boot所在的分区；
grub>setup (hd0) 注：把GRUB写到MBR上；

注解：
上面这步骤是根据 find /boot/stage1而来的，仔细看一下就明白了；现在我们一般安装很少会把/boot分区列为一个单独的分区；不过有的弟兄可能也喜欢这么做；所以还是有必要说一下为好；

四、GRUB的配置文件的menu.lst的写法；

对 于GRUB来说，如果没有配置menu.lst，无论是Linux版本的GRUB，还是WINGRUB，都会有命令行可用，通过命令行是一样能把操作系统 引导起来的；有些弟兄总以为menu.lst 配置错了， 或者在机器启动后出现grub>命令行模式就要重新安装系统，其实根本没有这个必要；只要学会GRUB的命令行的用法，根本没有必要重装系统；
menu.lst 位于/boot/grub目录中，也就是/boot/grub/menu.lst 文件；您可以用vi或您喜欢的编辑器来编辑他；如果您不会用vi，还是去学习一下吧；简单的用法怎么也得会，对不对？毕竟这个文档不是讲vi的用法的；
有的弟兄会说，我没有menu.lst怎么办？那就创建一个；用下面的命令；
[root@localhost ~]# touch /boot/grub/menu.lst

然后我们再做一个/boot/grub/menu.lst 的链接 /boot/grub/grub.conf
[root@localhost ~]# cd /boot/grub
[root@localhost ~]# ln -s menu.lst grub.conf 

现在我们来写GRUB的menu.lst了，因为/boot/grub/grub.conf是 /boot/grub/menu.lst的链接文件，改哪个都行。链接文件相当于Windows的快捷方式，这样可能能更好的理解；

1、menu.lst的写法之一；

首先我们看一下我的Fedora 4.0 中的/boot/grub/menu.lst 的内容；
default=0 
timeout=5
#splashimage=(hd0,6)/boot/grub/splash.xpm.gz
hiddenmenu
title Fedora Core (2.6.11-1.1369_FC4)
root (hd0,6)
kernel /boot/vmlinuz-2.6.11-1.1369_FC4 ro root=LABEL=/
initrd /boot/initrd-2.6.11-1.1369_FC4.img
title WinXp
rootnoverify (hd0,0)
chainloader +1

注解：
default=0 

default=0 是默认启动哪个系统，从0开始；每个操作系统的启动的定义都从title开始的，第一个title 在GRUB的启动菜单上显示为0,第二个启动为1，以此类推；
timeout=5 

注：表示在开机后，GRUB画面出现几秒后开始以默认启动；如果在启动时，移动上下键，则解除这一规则；
#splashimage=(hd0,6)/boot/grub/splash.xpm.gz 注：GRUB的背景画面，这个是可选项；我不喜欢GRUB的背景画面，所以加#号注掉，也可以删除；
hiddenmenu 

注解：隐藏GRUB的启动菜单，这项也是可选的，也可以用#号注掉；
一般的情况下对Linux操作系统的启动，一般要包括四行；title 行；root行；kernel 行；initrd 行；

1）在menu.lst中 ，通过 root (hd[0-n],y)来指定/boot 所在的分区；

title XXXXX 注：title 后面加一个空格，title 是小写的，后面可以自己定义；比如FC4，自己定义一个名字就行；
root (hd[0-n],y) ，在本例中，我们看到的是root (hd0,6) ,root (hd[0-n],y)表示的是/boot所在的分区；有时我们安装Linux的时候，大多是不设置/boot的，这时/boot和/所在的同一个分区； 这个root (hd[0-n],y)很重要，因为/boot目录中虽然有grub目录，最为重要的是还有kernel 和initrd文件，这是Linux能启动起来最为重要东西；
有的弟兄会问，root (hd[0-n],y)是怎么来的？
请参考：《在Linux系统中存储设备的两种表示方法》

2）在menu.lst中，kernel 命令行的写法；

kernel 一行，是通指定内核及Linux的/分区所在位置；
比如例子中是；
kernel /boot/vmlinuz-2.6.11-1.1369_FC4 ro root=LABEL=/ 

在这里以kernel 起始，指定Linux的内核的文件所处的绝对路径；因为内核是处在/boot目录中的， 如果/boot是独立的一个分区，则需要把boot省略；如果/boot是独立的分区，这行要写成:
kernel /vmlinuz-2.6.11-1.1369_FC4 ro root=LABEL=/ 

因 为/boot所处的分区已经在title 下一行root (hd[0-n],y)中指定了，所以就无需要再指明内核处在哪个分区了；另外Linux系统的硬盘分区的挂载配置文件在/etc/fstab ，原理是通过 mount /dev/hd[a-z]X /boot 来进行的；您可以对照着来理解；
ro 表示只读； root=LABEL=/ 来表示Linux的根所处的分区。LABEL=/ 这是硬盘分区格式化为相应文件系统后所加的标签；如果您不了解什么是标签，也可以直接以/dev/hd[a-z]X 或者/dev/sd[a-z]X来表示；就看您的Linux是根分区是在哪个分区了。比如我的是在/dev/hda7 ， 那这里就可以写成root=/dev/hda7；
如果查看系统运行所挂载的分区，请用 df -lh 来查看，就能明白是不是/boot是独立的分区，或者查看/etc/fstab也能知道；
[root@localhost ~]# df -lh
Filesystem 容量 已用 可用 已用% 挂载点
/dev/hda7 11G 9.2G 1.2G 90% /
/dev/shm 236M 0 236M 0% /dev/shm

在这个例子中，我们可以发现 /boot并没有出现只有/dev/hda7，这表示/boot并不是独立的一个分区；所有的东西都包含在/中；于是我们在/boot中查看内核版本；
[root@localhost ~]# ls /boot/vmlinuz*
/boot/vmlinuz-2.6.11-1.1369_FC4 注：看到内核vmlinuz所处的目录；

于是我们就可以这样kernel 这行了；
kernel /boot/vmlinuz-2.6.11-1.1369_FC4 ro root=/dev/hda7


3）initrd 命令行的写法；

如果是/boot独立一个分区，initrd 一行要把/boot中省略；如果/boot不是处于一个分区，而是和Linux的/分区处于同一分区，不应该省略；
比如我们在2）中用的例子；现在拿到这里，我们应该首先查看 /boot中的initrd的文件名到底是什么；
[root@localhost ~]# ls /boot/initrd*
/boot/initrd-2.6.11-1.1369_FC4.img

如果是通过df -lh 得知或查看/etc/fstab 也行， 得知/boot是独立的分区；这时initrd 应该写成；
initrd /initrd-2.6.11-1.1369_FC4.img

如果是 /boot不是独处一个分区，而是在/同一处一个分区， 则要写成；
initrd /boot/initrd-2.6.11-1.1369_FC4.img


4）menu.lst第一种写法的总结和实践；

在这里，我们只说重要的，不重要的就一带而过了；

1］用fdisk -l ；df -lh ；more /etc/fstab来确认分区情况；

我们过fdisk -l ；df -lh ; more /etc/fstab 来确认/boot所在的分区，及Linux的根分区所在位置；
比如我们确认/boot和Linux的/分区同处一个分区；
[root@localhost ~]# df -lh
Filesystem 容量 已用 可用 已用% 挂载点
/dev/hda7 11G 9.2G 1.2G 90% /
/dev/shm 236M 0 236M 0% /dev/shm

然后我们/etc/fstab 中,查看/分所在的分区或分区标签是什么；
[root@localhost ~]# more /etc/fstab
# This file is edited by fstab-sync - see ‘man fstab-sync‘ for details
LABEL=/ / ext3 defaults 1 1
/dev/devpts /dev/pts devpts gid=5,mode=620 0 0
/dev/shm /dev/shm tmpfs defaults 0 0
/dev/proc /proc proc defaults 0 0
/dev/sys /sys sysfs defaults 0 0
LABEL=SWAP-hda1 swap swap defaults 0 0
/dev/hdc /media/cdrecorder auto pamconsole,exec,noauto,managed 0 0

经 过上面的df -lh 和more /etc/fstab 的对照中得知，/boot并是独处一个分区，而是和/在同一个分区；这个Linux系统安装在/dev/hda7上，文件系统（此分区）的标签为 LABEL=/ ，/boot也是处于/dev/hda7 ，/dev/hda7也可以说是 root (hd0,6)；

2]查看内核vmlinuz的和initrd文件名的全称；

[root@localhost ~]# ls -lh /boot/vmlinuz*
-rw-r--r-- 1 root root 1.6M 2005-06-03 /boot/vmlinuz-2.6.11-1.1369_FC4
[root@localhost ~]# ls -lh /boot/initrd*
-rw-r--r-- 1 root root 1.1M 11月 26 22:30 /boot/initrd-2.6.11-1.1369_FC4.img


3]开始写menu.lst ；

我们根据上面所提到的，可以写成如下的样子；
default=0 
timeout=5
title FC4
root (hd0,6)
kernel /boot/vmlinuz-2.6.11-1.1369_FC4 ro root=LABEL=/ 
initrd /boot/initrd-2.6.11-1.1369_FC4.img

也可以写成；
default=0 
timeout=5
title FC4
root (hd0,6)
kernel /boot/vmlinuz-2.6.11-1.1369_FC4 ro root=/dev/hda7
initrd /boot/initrd-2.6.11-1.1369_FC4.img

注解：上面两个不同之处在于一指定Linux的根/所在的分区时，一个是用了文件系统的标签，另一个没有用标签；

2、menu.lst的写法之二，精简型；

本写法主要是把指定/boot所位于的所分区直接写入kernel 指令行；这样就省略了通过root (hd[0-n],y)来指定/boot所位于的分区；

1)第一种情况：/boot和Linux的/根分区在同一个分区；

有前面的那么多的讲解，menu.lst写法之二就好理解多了；也得分两种情况，咱们先把/boot并不是独处一个分区，而是和Linux的根分区处于同一个分区；我们以 4）menu.lst第一种方法的写法总结 的实例为例子；
default=0 
timeout=5
title FC4x
kernel (hd0,6)/boot/vmlinuz-2.6.11-1.1369_FC4 ro root=/dev/hda7
initrd (hd0,6)/boot/initrd-2.6.11-1.1369_FC4.img

注解：
title FC4x 注：自己为这个Linux 起个简单的名，以title开头，然后一个空格，后面就自己发挥吧，FC4或FC4x都行；
kernel 空格 (hd0,6)/boot/vmlinuz-2.6.11-1.1369_FC4 空格 ro 空格 root=/dev/hda7
kernel 这行这样理解 kernel (boot所在的分区)/boot/内核文件件全称 ro root=Linux根所位于的分区或标签
initrd 空格 (hd0,6)/boot/initrd-2.6.11-1.1369_FC4.img
initrd 这行可以这样理解 initrd (/boot所在的分区)/boot/内核文件名全称 

2）第二种情况：/boot独立一个分区，和Linux的根分区不是同一个分区；

比如我们查看到df -lh 得到的是
[root@localhost ~]# df -lh
Filesystem 容量 已用 可用 已用% 挂载点 
/dev/hda6 200M 120M 80M 60% /boot
/dev/hda7 11G 9.2G 1.2G 90% /

我们再进一行查看/etc/fstab 得知；
LABEL=/ / ext3 defaults 1 1
LABEL=/boot /boot ext3 defaults 1 2

所以我们应该写成如下的；
title FC4x
kernel (hd0,5)/vmlinuz-2.6.11-1.1369_FC4 ro root=LABEL=/
initrd (hd0,5)/initrd-2.6.11-1.1369_FC4.img

因为Linux的根分区是/dev/hda7，通过/etc/fstab和df -h的内容得知标签为 LABEL=/的分区就是/dev/hda7 ，所以有；
title FC4x
kernel (hd0,5)/vmlinuz-2.6.11-1.1369_FC4 ro root=/dev/hda7
initrd (hd0,5)/initrd-2.6.11-1.1369_FC4.img


五、通过GRUB命令行来启动Linux操作系统；

GRUB的命令行才是王道，如果知道怎么用命令行来启动操作系统，那理解menu.lst的写法也不难；也就是说在开机的时候，不用GRUB的菜单，通过GRUB的命令也是一样能把操作系统引导起来。
因为menu.lst的内容就是GRUB的一个一个的指令集合；是不是Linux这玩意很神奇？

1、为什么需要学习GRUB的命令行；

当 我们把GRUB的menu.lst写错的时候，或者丢掉了menu.lst的时，比如在开机的时候，GRUB会出现grub>类似的命令提示符，这 时需要我们用命令行启动系统；当然您可以不用定义GRUB的菜单 ，直接用命令行来启动系统，比如我现在就是，为了写GRUB的文档，就把menu.lst 删除了，直接用命令来启动系统；

2、用命令行来引导Linux操作系统的步骤；

通过命令行来引导操作系统的流程，也没有什么难的；无非是把指令手工输入到grub>提示符的后面；在这个过程中，tab键的命令补齐功能就显得很重要了。如果您不知道有哪些命令，可以输入help；

1）进入GRUB的命令行模式 grub>

如 果开机时，GRUB出现的是grub>，说明你没有/etc/grub/menu.lst ，您需要自己写一个才会GRUB的菜单，让我们来选择进入哪个系统。如果有GRUB的菜单，您可以按Ctrl+c组合键进入GRUB的命令行模式，会出现 grub> 提示符；
grub> 


2）获取帮助GRUB的 help

只要您在grub>提示符的后面输入help 就能得到GRUB所有的命令提示；
grub> help
blocklist FILE boot
cat FILE chainloader [--force] FILE
clear color NORMAL [HIGHLIGHT]
configfile FILE device DRIVE DEVICE
displayapm displaymem
find FILENAME geometry DRIVE [CYLINDER HEAD SECTOR [
halt [--no-apm] help [--all] [PATTERN ...]
hide PARTITION initrd FILE [ARG ...]
kernel [--no-mem-option] [--type=TYPE] makeactive
map TO_DRIVE FROM_DRIVE md5crypt
module FILE [ARG ...] modulenounzip FILE [ARG ...]
pager [FLAG] partnew PART TYPE START LEN
parttype PART TYPE quit
reboot root [DEVICE [HDBIAS]]
rootnoverify [DEVICE [HDBIAS]] serial [--unit=UNIT] [--port=PORT] [--
setkey [TO_KEY FROM_KEY] setup [--prefix=DIR] [--stage2=STAGE2_
terminal [--dumb] [--no-echo] [--no-ed terminfo [--name=NAME --cursor-address
testvbe MODE unhide PARTITION
uppermem KBYTES vbeprobe [MODE]

如果需要得到某个指令的帮助，就在 help 后面空一格，然后输入指令，比如；
grub>help kernel 


3）cat的用法；

cat 指令是用来查看文件内容的，有时我们不知道Linux的/boot分区，以及/根分区所在的位置，要查看/etc/fstab的内容来得知，这时，我们就 要用到cat (hd[0-n],y)/etc/fstab 来获得这些内容；注意要学会用tab键命令补齐的功能；
grub> cat ( 按tab 键会出来hd0或hd1之类的；
grub> cat (hd0, 注：输入hd0,然后再按tab键；会出来分区之类的；
grub> cat (hd0,6)
Possible partitions are:
Partition num: 0, Filesystem type unknown, partition type 0x7
Partition num: 4, Filesystem type is fat, partition type 0xb
Partition num: 5, Filesystem type is reiserfs, partition type 0x83
Partition num: 6, Filesystem type is ext2fs, partition type 0x83
Partition num: 7, Filesystem type unknown, partition type 0x83
Partition num: 8, Filesystem type is reiserfs, partition type 0x83
Partition num: 9, Filesystem type unknown, partition type 0x82

grub> cat (hd0,6)/etc/fstab 注：比如我想查看一下 (hd0,6)/etc/fstab的内容就这样输入；

LABEL=/ / ext3 defaults 1 1
/dev/devpts /dev/pts devpts gid=5,mode=620 0 0
/dev/shm /dev/shm tmpfs defaults 0 0
/dev/proc /proc proc defaults 0 0
/dev/sys /sys sysfs defaults 0 0
LABEL=SWAP-hda1 swap swap defaults 0 0
/dev/hdc /media/cdrecorder auto pamconsole,exec,noauto,
managed 0 0

有的弟兄可能会说，我不知道Linux安装在了哪个分区。那根据文件系统来判断一个一个的尝试总可以吧我；只要能cat出/etc/fstab就能为以后引导带来方便；
主 要查看/etc/fstab中的内容，主要是Linux的/分区及/boot是否是独立的分区；如果没有/boot类似的行，证明/boot和Linux 的/处于同一个硬盘分区；比如上面的例子中LABEL=/ 这行是极为重要的；说明Linux系统就安在标签为LABEL=/的分区中；
如果您的Linux系统/boot和/没有位于同一个分区，可能cat (hd[a-n],y) 查到的是类似下面的；
LABEL=/ / ext3 defaults 1 1
LABEL=/boot /boot ext3 defaults 1 2


4） root (hd[0-n,y) 指令来指定/boot所在的分区；

其实这个root (hd[0,n],y)是可以省略的，如果省略了，我们要在kerenl 命令中指定；我们前面已经说过 (hd[0-n],y) 硬盘分区的表示方法的用途；主要是用来指定 /boot所在的分区；
比如我们确认/boot和 (hd0,6)，所以就可以这样来输入root (hd0,6)
grub> root (hd0,6)

如果发现不对，可以重新来过；没有什么大不了的；

5） kernel 指令，用来指定Linux的内核，及/所在的分区；

kernel 这个指令可能初学者有点怕，不知道内核在哪个分区，及内核文件名的全称是什么。不要忘记tab键的命令补齐的应用；

如果我们已经通过root (hd[0-n],y) 指定了/boot所在的分区，语法有两个：

如果/boot和Linux的/位于同一个分区，应该是下面的一种格式；

kernel /boot/vmlinuz在这里按tab键来补齐，就看到内核全称了 ro root=/dev/hd[a-z]X

如果/boot有自己独立的分区，应该是；

kernel /vmlinuz在这里按tab键来补齐，就看到内核全称了 ro root=/dev/hd[a-z]X

在这里 root=/dev/hd[a-z]X 是Linux 的/根所位于的分区，如果不知道是哪个分区，就用tab出来的来计算，一个一个的尝试；或用cat (hd[0-n],y)/etc/fstab 中得到Linux的/所在的分区或分区的标签；
grub> kernel /boot/在这里按tab键；这样就列出/boot中的文件了； 
Possible files are: grub initrd-2.6.11-1.1369_FC4.img System.map-2.6.11-1.1369
_FC4 config-2.6.11-1.1369_FC4 vmlinuz-2.6.11-1.1369_FC4 grubBAK memtest86+-1.55
.1 xen-syms xen.gz

grub> kernel /boot/vmlinuz-2.6.11-1.1369_FC4 ro root=LABEL=/ 
[Linux-bzImage, setup=0x1e00, size=0x18e473]

注解： root=LABEL=/ 是Linux的/所在的分区的文件系统的标签；如果您知道Linux的/在哪个具体的分区，用root=/dev/hd[a-z]X来指定也行。比如下面的一行也是可以的；
grub> kernel /boot/vmlinuz-2.6.11-1.1369_FC4 ro root=/dev/hda7

也可以把/boot所在的分区的指定 root (hd[0-n],y)这行省掉，直接在kernel 中指定/boot所在的分区；所以就在下面的语法；
如果是/boot和Linux的根同处一个分区；
kernel (hd[0-n],y)/boot/vmlinuz ro root=/dev/hd[a-z]X

比如：
grub>kernel 

如果是/boot和Linux所在的根不在一个分区；则是；
kernel (hd[0-n],y)/vmlinuz ro root=/dev/hd[a-z]X 

grub> kernel (hd0,6)/boot/vmlinuz-2.6.11-1.1369_FC4 ro root=/dev/hda7 
[Linux-bzImage, setup=0x1e00, size=0x18e473]

或下面的输入，以cat 出/etc/fstab内容为准；
grub> kernel (hd0,6)/boot/vmlinuz-2.6.11-1.1369_FC4 ro root=LABEL=/
[Linux-bzImage, setup=0x1e00, size=0x18e473]


6）initrd 命令行来指定initrd文件；

grub> initrd /boot/initrd在这里tab 来补齐；
grub> initrd /boot/initrd-2.6.11-1.1369_FC4.img
[Linux-initrd @ 0x2e1000, 0x10e685 bytes]

如果/boot是独立的一个分区，应该是如下样子的语法；比如下面的；
grub> initrd /initrd在这里tab 来补齐；
grub> initrd /initrd-2.6.11-1.1369_FC4.img
[Linux-initrd @ 0x2e1000, 0x10e685 bytes]


7）boot 引导系统；

grub>boot 

前面的几个步骤都弄好 。就进入引导；尝试一下就知道了。。

8）引导Linux系统实例全程回放；

实例：/boot和Linux的/处于同一个硬盘分区；
grub> cat (hd0,6)/etc/fstab
# This file is edited by fstab-sync - see ‘man fstab-sync‘ for details
LABEL=/ / ext3 defaults 1 1
/dev/devpts /dev/pts devpts gid=5,mode=620 0 0
/dev/shm /dev/shm tmpfs defaults 0 0
/dev/proc /proc proc defaults 0 0
/dev/sys /sys sysfs defaults 0 0
LABEL=SWAP-hda1 swap swap defaults 0 0
/dev/hdc /media/cdrecorder auto pamconsole,exec,noauto,managed 0 0

grub> root (hd0,6)
Filesystem type is ext2fs, partition type 0x83

grub> kernel /boot/在这里按tab补齐，全列出/boot所有的文件；
Possible files are: grub initrd-2.6.11-1.1369_FC4.img System.map-2.6.11-1.1369_FC4 config-2.6.11-1.1369_FC4 vmlinuz-2.6.11-1.1369_FC4 
memtest86+-1.55.1 xen-syms xen.gz

grub> kernel /boot/vmlinuz-2.6.11-1.1369_FC4 ro root=/dev/hda7 注：输入
[Linux-bzImage, setup=0x1e00, size=0x18e473]

grub> initrd /boot/在这里按tab补齐
Possible files are: grub initrd-2.6.11-1.1369_FC4.img System.map-2.6.11-1.1369_FC4 config-2.6.11-1.1369_FC4 vmlinuz-2.6.11-1.1369_FC4 
memtest86+-1.55.1 xen-syms xen.gz

grub> initrd /boot/initrd-2.6.11-1.1369_FC4.img 注;输入intrd文件名的全名；
[Linux-initrd @ 0x2e1000, 0x10e685 bytes]

grub> boot

我们指定Linux的根时，可以用cat出来的fstab的内容中Linux的/分区文件系统标签来替代；也就是kernel 那行中 root=/dev/hd[a-z]X； 
grub> cat (hd0,6)/etc/fstab
# This file is edited by fstab-sync - see ‘man fstab-sync‘ for details
LABEL=/ / ext3 defaults 1 1
/dev/devpts /dev/pts devpts gid=5,mode=620 0 0
/dev/shm /dev/shm tmpfs defaults 0 0
/dev/proc /proc proc defaults 0 0
/dev/sys /sys sysfs defaults 0 0
LABEL=SWAP-hda1 swap swap defaults 0 0

/dev/hdc /media/cdrecorder auto pamconsole,exec,noauto,managed 0 0

grub> root (hd0,6)
Filesystem type is ext2fs, partition type 0x83

grub> kernel /boot/在这里按tab补齐，全列出/boot所有的文件；
Possible files are: grub initrd-2.6.11-1.1369_FC4.img System.map-2.6.11-1.1369_FC4 config-2.6.11-1.1369_FC4 vmlinuz-2.6.11-1.1369_FC4 
memtest86+-1.55.1 xen-syms xen.gz

grub> kernel /boot/vmlinuz-2.6.11-1.1369_FC4 ro root=LABEL=/ 
[Linux-bzImage, setup=0x1e00, size=0x18e473]

grub> initrd /boot/在这里按tab补齐
Possible files are: grub initrd-2.6.11-1.1369_FC4.img System.map-2.6.11-1.1369_FC4 config-2.6.11-1.1369_FC4 vmlinuz-2.6.11-1.1369_FC4 grubBAK
memtest86+-1.55.1 xen-syms xen.gz

grub> initrd /boot/initrd-2.6.11-1.1369_FC4.img 注;输入intrd文件名的全名；
[Linux-initrd @ 0x2e1000, 0x10e685 bytes]

grub> boot

如果是/boot和Linux的根分区不在同一个分区，要把kernel和initrd 指令中的/boot去掉，也就是/vmlinuzMMMMMM 或 /initrdNNNN
也 可以不用root (hd[0-n]来指定/boot所在分区，要在kernel 和initrd 中指定；比如Linux的/根所位于的分区和/boot所位于的分区都是(hd0,6)，并且我们cat出来的/etc/fstab是Linux的/根分 区的文件系统的标签为LABEL=/，引导操作系统的例子如下；
grub>kernel (hd0,6)/boot/vmlinuz-2.6.11-1.1369_FC4 ro root=LABEL=/
grub>initrd (hd0,6)/boot/initrd-2.6.11-1.1369_FC4.img
grub>boot 

或
grub>kernel (hd0,6)/boot/vmlinuz-2.6.11-1.1369_FC4 ro root=/dev/hda7 
grub>initrd (hd0,6)/boot/initrd-2.6.11-1.1369_FC4.img
grub>boot 

如果/boot位于 /dev/hda6，也就是(hd0,5)，Linux的根/位于分区/dev/hda7，并且我们cat 出来的/etc/fstab 中/分区的标签为 LABEL=/。下面的两种方法都可以引导；
grub>kernel (hd0,5)/vmlinuz-2.6.11-1.1369_FC4 ro root=LABEL=/
grub>initrd (hd0,5)/initrd-2.6.11-1.1369_FC4.img
grub>boot 

或
grub>kernel (hd0,5)/vmlinuz-2.6.11-1.1369_FC4 ro root=/dev/hda7 
grub>initrd (hd0,5)/initrd-2.6.11-1.1369_FC4.img
grub>boot 


六、通过GRUB引导Windows操作系统；


1、通过编辑 menu.lst 来引导Windows 系统；

如果您的Windows所处于的分区在(hd0,0)，可以在menu.lst 加如下的一段就能引导起来了；
title WinXp
rootnoverify (hd0,0)
chainloader +1

如果您的机器有两块硬盘，而Windows 位于第二个硬盘的第一个分区，也就是(hd1,0)
您可以用grub的map来指令来操作把两块硬盘的序列对调，这样就不用在BIOS中设置了；在menu.lst中加如下的内容，比如下面的；
title WinXp
map (hd0) (hd1)
map (hd1) (hd0)
rootnoverify (hd0,0)
chainloader +1
makeactive

如果Windows的分区不位于硬盘的第一个分区怎么办呢？比如在(hd0,2)；
这个也好办吧，把rootnoverify 这行的(hd0,0)改为 (hd0,2)
title WinXp
rootnoverify (hd0,2)
chainloader +1
makeactive

如果Windows的在第二个硬盘的某个分区，比如说是位于(hd1,2)，则要用到map指令；
title WinXp
map (hd0) (hd1)
map (hd1) (hd0)
rootnoverify (hd1,2)
chainloader +1
makeactive

如 果有多个Windows 系统，怎么才能引导出来呢？应该用hide 和unhide指令操作；比如我们安装了两个Windows ，一个是位于(hd0,0)的windows 98 ，另一个是安装的是位于(hd0,1)的WindowsXP；这时我们就要用到hide指令了；
title Win98
unhide (hd0,0)
hide (hd0,1)
rootnoverify (hd0,0)
chainloader +1
makeactive

title WinXP 
unhide (hd0,1)
hide (hd0,0)
rootnoverify (hd0,1)
chainloader +1
makeactive


2、通过GRUB指令来引导Windows ；

其实我们会写menu.lst了，在menu.lst中的除了title外，都是一条条指令；如果我们启动Windows ，只是输入指令就行了；
比如 Windows的分区在 (hd0,0)，我们在开机后，按ctrl+c ，进入GRUB的命令模式；就可以用下面的
grub> rootnoverify (hd0,0)
grub> chainloader +1
grub> boot 

其它同理... ...

七、GRUB丢失或损坏的应对策略；

如果GRUB是Linux版本才出会这样的问题；WINGRUB可以不写在MBR上；所以不会出现这样的问题。WINGRUB用起来比较简单。menu.lst 和命令行的用法和Linux版本的GRUB是一样的；

1、由于重新安装Windows或其它未知原因而导致GRUB的丢失；

您可以通过系统安装盘、livecd进入修复模式；
请参考：《Linux 系统的单用户模式、修复模式、跨控制台登录在系统修复中的运用》
首先：您根据前面所说grub-install来安装GRUB到/boot所在的分区；要仔细看文档，/boot是不是处于一个独立的分区是重要的，执行的命令也不同；
其次：要执行grub ，然后通过 root (hd[0-n],y)来指定/boot所位于的分区，然后接着执行 setup (hd0)，这样就写入MBR了，比如下面的例子；
grub>root (hd0,6)
grub>setup (hd0)
grub>quit

重新引导就会再次出现MBR的菜单了或命令行的提示符了； 


2、如果出现GRUB提示符，而不出现GRUB的菜单，如何引导系统；

存在的问题可能是/boot/grub/menu.lst丢失，要自己写一个才行；您可以用命令行来启动系统，进入系统后写一写menu.lst就OK了。前面已经谈过了；
写好后还要建一个grub.conf的链接，如下：
[root@localhost ~]# cd /boot/grub
[root@localhost grub]# ln -s menu.lst grub.conf


八、关于GRUB的未尽事宜；

GRUB有很多内容，比如对BSD的引导，还有一些其它指令的用法，我并没有在本文提到；主要我目前还未用到，如果您需要了解更多，请查看 《GNU GRUB 手册和FAQ》

grub paramiter & menu.list