一介绍：

`.ARM.exidx` is the section containing information for unwinding the stack. If your C program has functions that print out a stack backtrace, the functions will likely depend on this section being present.

相关的编译选项 `-funwind-tables

二问题：

cannot locate symbol "__exidx_start" referenced by

可以在linker script中添加（诸如此类的未定义现象可以在linker script中解决 或者通过编译选项解决）

__exidx_start = .;

 .ARM.exidx : { *(.ARM.exidx* .gnu.linkonce.armexidx.*) } >sram

 __exidx_end = .;