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    SubjectRe: Linux 2.6.27.27
    On 07/20/2009 06:08 PM, Linus Torvalds wrote:
    >
    > On Mon, 20 Jul 2009, Krzysztof Oledzki wrote:
    >> No problem. Please let me know what should I do to help tracking this issue.
    >
    > Can you build two kernels: one with -fwrapv, and one with
    > -fno-strict-overflow, and then verify that
    >
    > - they are otherwise identical (ie exact same source code, same compiler
    > etc)
    >
    > - verify that yes, the -fwrapv kernel works, the other does not. Just to
    > avoid the confusion that obviously exists with Debian/sid binutils
    > upgrades that _also_ happens result in nonbootable kernels.
    >
    > - upload the 'vmlinux' images somewhere (I'm not sure what the limits for
    > binary attachments are at the kernel bugzilla, but that would be the
    > logical place)
    >
    > In fact, it would be nice to have a third "identical" kernel build, except
    > with neither -fwrapv/-fno-strict-overflow.
    >
    > Linus

    I might be seeing a slightly different bug, but in case it's helpful,
    the behaviour here on Fedora rawhide with gcc-4.4.0-14.x86_64 and
    binutils-2.19.51.0.11-27.fc12.x86_64 is that I get various .o files that
    come out as completely empty files (or in one case as a precisely 64K
    sized file that gives a "File format not recognized" error"), and the
    latest 2.6.31-rc git can't be built at all.

    If I replace -fno-strict-overflow with -fwrapv in Makefile everything
    builds and runs fine.

    Interestingly though, "-fno-strict-overflow -v" also gives me a good
    kernel, and comparing the assembly for one of the affected files doesn't
    show any difference between -fwrapv and -fno-strict-overflow.

    Marc


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