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    SubjectRe: [PATCH] x86: unify x86 Makefile(s)
    On Sat, Dec 29, 2007 at 12:13:24AM +0200, Adrian Bunk wrote:
    > On Fri, Dec 28, 2007 at 10:23:41PM +0100, Sam Ravnborg wrote:
    > >...
    > > Noteworthy remarks on the unification:
    > >...
    > > - -funit-at-a-time should be easy to unify but it looks like we have a bug
    > > in 32 bit. We only enable -funit-at-a-time for gcc less than 0400 if they
    > > support it
    >
    > No, we _dis_able it on 32bit if a gcc < 4.0 supports it.
    I have:
    $ gcc --version
    gcc (GCC) 4.1.2 20070925 (Red Hat 4.1.2-33)

    And with the current code in arch/x86/Makefile_32 I do not
    have -funit-at-a-time.

    Sample gcc cammandline:
    gcc -m32 -Wp,-MD,init/.do_mounts_rd.o.d -nostdinc -isystem /usr/lib/gcc/x86_64-redhat-linux/4.1.2/include -D__KERNEL__ -Iinclude -include include/linux/autoconf.h -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs -fno-strict-aliasing -fno-common -Werror-implicit-function-declaration -Os -pipe -msoft-float -mregparm=3 -freg-struct-return -mpreferred-stack-boundary=2 -march=i686 -mtune=pentium3 -mtune=generic -ffreestanding -maccumulate-outgoing-args -DCONFIG_AS_CFI=1 -DCONFIG_AS_CFI_SIGNAL_FRAME=1 -Iinclude/asm-x86/mach-generic -Iinclude/asm-x86/mach-default -fomit-frame-pointer -fno-stack-protector -Wdeclaration-after-statement -Wno-pointer-sign -D"KBUILD_STR(s)=#s" -D"KBUILD_BASENAME=KBUILD_STR(do_mounts_rd)" -D"KBUILD_MODNAME=KBUILD_STR(mounts)" -c -o init/do_mounts_rd.o init/do_mounts_rd.c


    This is the relevant snippet from the Makefile:
    KBUILD_CFLAGS += $(shell if [ $(call cc-version) -lt 0400 ] ; then echo $(call cc-option,-fno-unit-at-a-time); fi ;)

    It reads:
    If gcc version is less than 4.00 then enable -funit-at-a-time only for gcc that supports it.
    -funit-at-a-time is NOT enabled for gcc >= 4.00

    So it will enable -funit-at-a-time for gcc 3.4 as it is now.
    Which was what we wanted to avoid..
    So I see no reason not to enable it uncondintionally (if gcc supports it) as we have
    used it for 3.4 for as long as we have introduced -funit-at-a-time.

    Sam


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