请教一下vmlinux.lds.S链接脚本

super皮波

arm体系结构
如下的DISCARD这个段是干嘛用的？
"/DISCARD/"  是个段名？为什么两边要加上"/"呢？
多谢
SECTIONS
{
        /*
         * XXX: The linker does not define how output sections are
         * assigned to input sections when there are multiple statements
         * matching the same input section name.  There is no documented
         * order of matching.
         *
         * unwind exit sections must be discarded before the rest of the
         * unwind sections get included.
         */
        /DISCARD/ : {
                *(.ARM.exidx.exit.text)
                *(.ARM.extab.exit.text)
                ARM_CPU_DISCARD(*(.ARM.exidx.cpuexit.text))
                ARM_CPU_DISCARD(*(.ARM.extab.cpuexit.text))
                ARM_EXIT_DISCARD(EXIT_TEXT)
                ARM_EXIT_DISCARD(EXIT_DATA)
                EXIT_CALL
#ifndef CONFIG_HOTPLUG
                *(.ARM.exidx.devexit.text)
                *(.ARM.extab.devexit.text)
#endif
#ifndef CONFIG_MMU
                *(.fixup)
                *(__ex_table)
#endif
#ifndef CONFIG_SMP_ON_UP
                *(.alt.smp.init)
#endif
                *(.discard)
                *(.discard.*)
        }

arm-linux-gcc

ld.pdf中有写

The special output section name ‘/DISCARD/’ may be used to discard input sections. Any
input sections which are assigned to an output section named ‘/DISCARD/’ are not included
in the output file.

super皮波

回复 2# arm-linux-gcc
多谢
那我直接不把这些section链接进来不就行了嘛，为嘛要特别说明一下？


   

Tinnal

回复 3# super皮波

从
unwind exit sections must be discarded before the rest of the
         * unwind sections get included.

这句话看来，应该是想法unwind整体信息的exit部分剔除出去。但又不想一个一个的加进来，所以采用了减法。

假设 unwind total = A + B  + C + D
则 include A + include B + include C = include total - exclude C

这样还能防止以后unwind信息出现扩展时必须更改链接脚本的。