[PATCH] powerpc: Allow selection of CONFIG_LD_DEAD_CODE_DATA_ELIMINATION

[Christophe Leroy]

This option does dead code and data elimination with the linker by
compiling with -ffunction-sections -fdata-sections and linking with
--gc-sections.

By selecting this option on mpc885_ads_defconfig,
vmlinux LOAD segment size gets reduced by 10%

Program Header before the patch:
    LOAD off    0x00010000 vaddr 0xc0000000 paddr 0x00000000 align 2**16
         filesz 0x0036eda4 memsz 0x0038de04 flags rwx

Program Header after the patch:
    LOAD off    0x00010000 vaddr 0xc0000000 paddr 0x00000000 align 2**16
         filesz 0x00316da4 memsz 0x00334268 flags rwx

Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxx>
---
 arch/powerpc/Kconfig | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 8fe4353be5e3..e1fac49cf465 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -888,6 +888,14 @@ config PPC_MEM_KEYS
 
 	  If unsure, say y.
 
+config PPC_UNUSED_ELIMINATION
+	bool "Eliminate unused functions and data from vmlinux"
+	default n
+	select LD_DEAD_CODE_DATA_ELIMINATION
+	help
+	  Select this to do dead code and data elimination with the linker
+	  by compiling with -ffunction-sections -fdata-sections and linking
+	  with --gc-sections.
 endmenu
 
 config ISA_DMA_API
-- 
2.13.3