linux-kernel - [PATCH 0/4] function/data-sections

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Date:	Thu, 29 Jul 2010 01:47:52 +0200
From:	Denys Vlasenko <vda.linux@...glemail.com>
To:	Michal Marek <mmarek@...e.cz>,
	linux-kbuild <linux-kbuild@...r.kernel.org>,
	linux-arch@...r.kernel.org,
	Parisc List <linux-parisc@...r.kernel.org>
Cc:	lkml <linux-kernel@...r.kernel.org>,
	Sam Ravnborg <sam@...nborg.org>,
	Tim Abbott <tabbott@...lice.com>,
	Tim Bird <tim.bird@...sony.com>,
	James Bottomley <James.Bottomley@...senpartnership.com>,
	Matt Fleming <matt@...sole-pimps.org>,
	Arnd Bergmann <arnd@...db.de>,
	Anders Kaseorg <andersk@....edu>,
	Andi Kleen <andi@...stfloor.org>,
	Stephen Rothwell <sfr@...b.auug.org.au>,
	Denys Vlasenko <vda.linux@...glemail.com>
Subject: [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)

Signed-off-by: Denys Vlasenko <vda.linux@...glemail.com>
Acked-by: Sam Ravnborg <sam@...nborg.org>


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(-)

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