Messages in this thread | | | From | Mathieu Malaterre <> | Date | Tue, 17 Apr 2018 19:10:46 +0200 | Subject | Re: [PATCH] powerpc: Allow selection of CONFIG_LD_DEAD_CODE_DATA_ELIMINATION |
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On Tue, Apr 17, 2018 at 6:49 PM, Christophe LEROY <christophe.leroy@c-s.fr> wrote: > > > Le 17/04/2018 à 18:45, Mathieu Malaterre a écrit : >> >> On Tue, Apr 17, 2018 at 12:49 PM, Christophe Leroy >> <christophe.leroy@c-s.fr> wrote: >>> >>> 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@c-s.fr> >>> --- >>> 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: > > > Which version of GCC do you use ?
$ powerpc-linux-gnu-gcc --version powerpc-linux-gnu-gcc (Debian 6.3.0-18) 6.3.0 20170516 Copyright (C) 2016 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
this is simply coming from:
$ apt-cache policy crossbuild-essential-powerpc crossbuild-essential-powerpc: Installed: 12.3 Candidate: 12.3 Version table: *** 12.3 500 500 http://ftp.fr.debian.org/debian stretch/main amd64 Packages 500 http://ftp.fr.debian.org/debian stretch/main i386 Packages 100 /var/lib/dpkg/status
> Can you provide the generated System.map with and without that option active > ?
$ du -sh g4/System.map.* 1.7M g4/System.map.with 1.8M g4/System.map.without
Will send them by private emails.
> Thanks > Christophe > > >> >> --- >> 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 >>> >
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