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    SubjectRe: [PATCH] Compile failure fix for ppc on 2.6.17-rc4-mm3 (2nd attempt) (Mel Gorman) wrote:
    > (Resending with Andrew's email address correct this time)
    > For the last few -mm releases, kernels built for an old RS6000 failed to
    > compile with the message;
    > arch/powerpc/kernel/built-in.o(.init.text+0x77b4): In function `vrsqrtefp':
    > : undefined reference to `__udivdi3'
    > arch/powerpc/kernel/built-in.o(.init.text+0x7800): In function `vrsqrtefp':
    > : undefined reference to `__udivdi3'
    > make: *** [.tmp_vmlinux1] Error 1

    A function with a name like that doesn't _deserve_ to compile.

    But actually vrsqrtefp() doesn't call __udivdi3 - the error lies somewhere
    else in the kernel and the toolchain gets it wrong, so we don't know where.

    The way I usually hunt this problem down is to build the .s files (make
    arch/powerpc/kernel/foo.s) and then grep around, find the offending C

    If the problem is specific to powerpc then a

    diffstat 2.6.17.rc4-mm3 | grep powerpc

    will narrow down the number of files to be searched by rather a lot.

    > 2.6.17-rc5 is not affected but I didn't search for the culprit patch in
    > -mm. The following patch adds an implementation of __udivdi3 for plain old
    > ppc32. This may not be the correct fix as Google tells me that __udivdi3
    > has been replaced by calls to do_div() in a number of cases. There was no
    > obvious way to do that for vrsqrtefp, hence this workaround. The patch should
    > be acked, rejected or replaced by a ppc expert.

    Yes, we've traditionally avoided adding the 64-bit divide library functions.
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      Last update: 2006-05-26 18:52    [W:0.021 / U:4.016 seconds]
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