Messages in this thread | | | Date | Fri, 26 May 2006 09:49:24 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH] Compile failure fix for ppc on 2.6.17-rc4-mm3 (2nd attempt) |
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mel@csn.ul.ie (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 function.
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 has been replaced by calls to do_div() in a number of cases.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. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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