tree 59cfd4ebc0ea13e799b9e4393740591f9e16985d
parent a5967db9af51a84f5e181600954714a9e4c69f1f
author Nicholas Piggin <npiggin@gmail.com> 1472041760 +1000
committer Michal Marek <mmarek@suse.com> 1473410820 +0200

kbuild: allow archs to select link dead code/data elimination

Introduce LD_DEAD_CODE_DATA_ELIMINATION option for architectures to
select to build with -ffunction-sections, -fdata-sections, and link
with --gc-sections. It requires some work (documented) to ensure all
unreferenced entrypoints are live, and requires toolchain and build
verification, so it is made a per-arch option for now.

On a random powerpc64le build, this yelds a significant size saving,
it boots and runs fine, but there is a lot I haven't tested as yet, so
these savings may be reduced if there are bugs in the link.

    text      data        bss        dec   filename
11169741   1180744    1923176	14273661   vmlinux
10445269   1004127    1919707	13369103   vmlinux.dce

~700K text, ~170K data, 6% removed from kernel image size.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michal Marek <mmarek@suse.com>