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function/data-sections

Denys Vlasenko linux-arch linux-kbuild linux-parisc lkml 1 version In review

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  1. v1 Latest4 patches 6 repliesIn review

Patches in v1 No applies recorded yet

#Subject and filesSizeRepliesApplied
1/4modpost: support objects with more than 64k sectionsscripts/mod/file2alias.c scripts/mod/modpost.c scripts/mod/modpost.h+122 -291 reply
2/4module linker script: coalesce function and data sectionsscripts/module-common.lds+23 -05 replies
3/4kernel linker stripts: accomodate function and data sectionsarch/frv/kernel/vmlinux.lds.S arch/ia64/scripts/check-segrel.lds arch/m68knommu/kernel/vmlinux.lds.S +6 more+25 -50 replies
4/4boot linker stripts: accomodate function and data sectionsarch/alpha/boot/bootloader.lds arch/arm/boot/bootp/bootp.lds arch/cris/boot/compressed/decompress_v10.lds +16 more+43 -120 replies

Reviews trailers per patch

All 4 patches have a Reviewed-by or Acked-by of their own; the series has one for all of them.

PatchSam Ravnborg
SeriesA-b
1/4A-b
2/4A-b
3/4A-b
4/4A-b

Trailers given in replies are filled; those carried in the patches from earlier versions are outlined with dashes.

Read the v1 thread

Cover letter [PATCH 0/4] function/data-sections

Hi Michal,

Please take this patch series onto linux-kbuild.

Most of work needed for working -ffunction-sections -fdata-sections build is already in the mainline, but a few bits are still missing. In order to have a working kernel with this make invocation:
make KCFLAGS="-ffunction-sections -fdata-sections"
we need these patches:

modpost: support objects with more than 64k sections
This patch is in -mm, it still did not reach mainline, thus resending. Sam suggested some readability improvements.
module linker script: coalesce function and data sections kernel linker stripts: accomodate function and data sections boot linker stripts: accomodate function and data sections

Please see individual patches for more detailed changelogs.

A rough idea what sort of size savings are achievable with section garbage collection:
Kernel:
text data bss dec hex filename
8299299 857324 785348 9941971 97b3d3 2.6.35-rc4/vmlinux 7566908 832388 717844 9117140 8b1dd4 2.6.35-rc4-fsgs/vmlinux
-9.2% -2.9% -9.0% -8.6%
The largest module in the build:

 451009  54640   2224  507873  7bfe1 2.6.35-rc4/fs/xfs/xfs.ko
 450521  54292   2202  507015  7bc87 2.6.35-rc4-fsgs/fs/xfs/xfs.ko

(negligible size change since section garbage collection for modules is not done. TODO: figure out how to do it)

Denys Vlasenko (4):
modpost: support objects with more than 64k sections module linker script: coalesce sections
kernel linker stripts: accomodate function and data sections boot linker stripts: accomodate function and data sections

 arch/alpha/boot/bootloader.lds               |    6 +-
 arch/arm/boot/bootp/bootp.lds                |    1 +
 arch/cris/boot/compressed/decompress_v10.lds |    3 +
 arch/cris/boot/compressed/decompress_v32.lds |    3 +
 arch/cris/boot/rescue/rescue_v10.lds         |    2 +
 arch/cris/boot/rescue/rescue_v32.lds         |    3 +
 arch/frv/kernel/vmlinux.lds.S                |    1 -
 arch/h8300/boot/compressed/vmlinux.lds       |    2 +
 arch/h8300/boot/compressed/vmlinux.scr       |    1 +
 arch/ia64/hp/sim/boot/bootloader.lds         |    6 +-
 arch/ia64/scripts/check-segrel.lds           |    4 +-
 arch/m32r/boot/compressed/vmlinux.lds.S      |    6 +-
 arch/m32r/boot/compressed/vmlinux.scr        |    1 +
 arch/m68knommu/kernel/vmlinux.lds.S          |    1 +
 arch/mips/lasat/image/romscript.normal       |    1 +
 arch/mn10300/boot/compressed/vmlinux.lds     |    1 +
 arch/parisc/kernel/vmlinux.lds.S             |    1 +
 arch/powerpc/boot/zImage.coff.lds.S          |    2 +
 arch/powerpc/boot/zImage.lds.S               |    2 +
 arch/powerpc/boot/zImage.ps3.lds.S           |    2 +
 arch/sh/boot/compressed/vmlinux.scr          |    1 +
 arch/sh/kernel/vsyscall/vsyscall.lds.S       |    2 +-
 arch/x86/boot/setup.ld                       |    3 +-
 arch/x86/kernel/acpi/realmode/wakeup.lds.S   |    1 +
 arch/x86/kernel/vmlinux.lds.S                |    1 +
 arch/xtensa/boot/boot-elf/boot.lds.S         |    5 +-
 arch/xtensa/boot/boot-redboot/boot.ld        |    5 +-
 include/asm-generic/vmlinux.lds.h            |   18 ++++-
 scripts/mod/file2alias.c                     |    6 +-
 scripts/mod/modpost.c                        |  102 +++++++++++++++++++-------
 scripts/mod/modpost.h                        |   43 +++++++++++
 scripts/module-common.lds                    |   23 ++++++
 32 files changed, 213 insertions(+), 46 deletions(-)