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    SubjectRe: [tip:x86/urgent] x86, hweight: Fix UML boot crash
    Note: I have applied this  because it fixes a regression, but it bugs
    the living bejeezus out of me that the saner patch:

    diff --git a/arch/um/include/asm/arch_hweight.h
    b/arch/um/include/asm/arch_hweight.h
    new file mode 100644
    index 0000000..c656cf4
    --- /dev/null
    +++ b/arch/um/include/asm/arch_hweight.h
    @@ -0,0 +1,6 @@
    +#ifndef _ASM_UM_HWEIGHT_H
    +#define _ASM_UM_HWEIGHT_H
    +
    +#include <asm-generic/bitops/arch_hweight.h>
    +
    +#endif
    ... supposedly didn't work. As such, I consider this a temporary kluge
    until a proper solution is found. From a code-cleanliness perspective,
    this patch is awful.

    -hpa


    On 06/09/2010 03:07 PM, tip-bot for Borislav Petkov wrote:
    > Commit-ID: cc7f0a7b3004a4ca0bfef0e1ca79f2e0da6ca1b0
    > Gitweb: http://git.kernel.org/tip/cc7f0a7b3004a4ca0bfef0e1ca79f2e0da6ca1b0
    > Author: Borislav Petkov <bp@alien8.de>
    > AuthorDate: Sun, 30 May 2010 19:03:46 +0200
    > Committer: H. Peter Anvin <hpa@linux.intel.com>
    > CommitDate: Wed, 9 Jun 2010 14:23:29 -0700
    >
    > x86, hweight: Fix UML boot crash
    >
    > UML apparently cannot stomach callee reg-saving trickery introduced
    > with d61931d89be506372d01a90d1755f6d0a9fafe2d (x86: Add optimized
    > popcnt variants) for reasons currently unknown, and oopses during
    > boot: http://marc.info/?l=linux-kernel&m=127522065202435&w=2
    >
    > Go ahead and fall back to the software hweight* routines on UML.
    >
    > LKML-Reference: <201005271944.09541.toralf.foerster@gmx.de>
    > Tested-by: Toralf Förster <toralf.foerster@gmx.de>
    > Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>
    > LKML-Reference: <20100530170346.GC1565@liondog.tnic>
    > Signed-off-by: Borislav Petkov <bp@alien8.de>
    > Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
    > Cc: Boaz Harrosh <bharrosh@panasas.com>
    > Cc: Jeff Dike <jdike@addtoit.com>
    > Cc: Andrew Morgon <akpm@linux-foundation.org>
    > ---
    > arch/x86/include/asm/bitops.h | 4 ++++
    > 1 files changed, 4 insertions(+), 0 deletions(-)
    >
    > diff --git a/arch/x86/include/asm/bitops.h b/arch/x86/include/asm/bitops.h
    > index 545776e..c9dad12 100644
    > --- a/arch/x86/include/asm/bitops.h
    > +++ b/arch/x86/include/asm/bitops.h
    > @@ -444,7 +444,11 @@ static inline int fls(int x)
    >
    > #define ARCH_HAS_FAST_MULTIPLIER 1
    >
    > +#ifdef CONFIG_UML
    > +#include <asm-generic/bitops/arch_hweight.h>
    > +#else
    > #include <asm/arch_hweight.h>
    > +#endif
    >
    > #include <asm-generic/bitops/const_hweight.h>
    >

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