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    SubjectRe: [REGRESSION] Recent change to kernel spikes out ccache/distcc
    On Wed, Jan 07, 2009 at 01:48:03PM +0000, Jan Beulich wrote:
    > >>> Sam Ravnborg <sam@ravnborg.org> 07.01.09 14:23 >>>
    > >On Wed, Jan 07, 2009 at 12:35:09PM +0000, Jan Beulich wrote:
    > >> >>> Sam Ravnborg <sam@ravnborg.org> 07.01.09 12:31 >>>
    > >> >What is the gain/pain ratio here?
    > >>
    > >> Certainly depends on the pov - it reduces the kernel module (disk) image
    > >> sizes quite a bit, so from a distro perspective its a move against the ever
    > >> growing package sizes (and the disk space) hundreds or even thousands
    > >> of modules require.
    > >
    > >The kernel modules seldom export anything so the benefit is minimal here.
    >
    > Not really, for highly modular distro kernels.
    >
    > >I did a 15 minutes hack to try ripping the .c -> .s -> .o stuff out.
    >
    > Looks good to me. In case you decide to revert the stuff for .29, I'll
    > merge this into my patch.
    As it stand now it:
    1) breaks sparc32 build
    2) causes regression with distcc/ccache use when MODVERSIONS are enabled
    3) the concept is under discussion

    So I will have to revert it somehow.
    I will look into during a partial revert though as your patches had some stuff
    in them I like to keep or which does not harm (genksyms change for instance).

    >
    > >Jan - I need some hard numbers to convince me that stripping the
    > >__crc symbols is worth it.
    >
    > The on-disk size of the modules in my builds is reduced by about 5% with
    > this patch (but I can't immediately tell how much of this is due to __crc_*
    > vs. other symbol stripping).

    But if only on-disk size is your primary concern then another patch
    of Jan Engelhardt would be a bigger win:

    build: install modules compressed
    ---
    scripts/Makefile.modinst | 2 +-
    1 files changed, 1 insertions(+), 1 deletions(-)

    diff --git a/scripts/Makefile.modinst b/scripts/Makefile.modinst
    index efa5d94..c3421a1 100644
    --- a/scripts/Makefile.modinst
    +++ b/scripts/Makefile.modinst
    @@ -17,7 +17,7 @@ __modinst: $(modules)
    @:

    quiet_cmd_modules_install = INSTALL $@
    - cmd_modules_install = mkdir -p $(2); cp $@ $(2) ; $(mod_strip_cmd) \
    $(2)/$(notdir $@)
    + cmd_modules_install = mkdir -p $(2); cp $@ $(2) ; \
    $(mod_strip_cmd) $(2)/$(notdir $@); gzip -9f $(2)/$(notdir $@)
    # Modules built outside the kernel source tree go into extra by default
    INSTALL_MOD_DIR ?= extra


    (cut'n'paste so will not apply direct)

    It does not decrease the size of vmlinux but the > 1000 modules are compressed.

    The patch will in some form be present in kbuild-next.git when I open up
    for that.
    Sam


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