Re: [PATCH] powerpc: Allow selection of CONFIG_LD_DEAD_CODE_DATA_ELIMINATION
From: Mathieu Malaterre <hidden>
Date: 2018-04-17 16:45:51
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On Tue, Apr 17, 2018 at 12:49 PM, Christophe Leroy [off-list ref] wrote:
quoted hunk ↗ jump to hunk
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 <redacted> --- 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
Just for reference, I cannot boot my Mac Mini G4 anymore (yaboot). The messages I can see (prom_init) are: --- done copying OF device tree... Building dt strings... Building dt structure... Device tree strings 0x01100000 -> 0x01100e02 Device tree struct 0x01101000 -> 0x01109000 Quiescing Open Firmware ... Booting Linux via __start() @ 0x00140000 ... _ ---
config ISA_DMA_API -- 2.13.3