Re: [PATCH 0/7] gcov kernel support

From: Segher Boessenkool
Date: Fri May 23 2008 - 17:54:33 EST

Sounds like your toolchain was built without biarch support, but you're
using it for the 32-bit parts of the kernel anyway. Which works as long
as you're not using any libraries, but now you need libgcov.a .


What does

powerpc64-unknown-linux-gnu-gcc -v


y:/home/akpm> /opt/crosstool/gcc-4.1.0-glibc-2.3.6/powerpc64-unknown-linux-gnu/bin/ powerpc64-unknown-linux-gnu-gcc -v
Using built-in specs.
Target: powerpc64-unknown-linux-gnu
Configured with: /home/axboe/crosstool-0.43/build/powerpc64-unknown-linux-gnu/gcc -4.1.0-glibc-2.3.6/gcc-4.1.0/configure --target=powerpc64-unknown-linux-gnu --host=x86_64-host_unknown-linux-gnu --prefix=/opt/crosstool/gcc-4.1.0-glibc-2.3.6/powerpc64-unknown-linux- gnu


That's the culprit. I believe 4.1.0 enables multilib by default on PowerPC
compilers that target 64-bit by default (the patch for that is dated almost
a full year before the 4.1.0 release). I have no idea why crosstool
disables this support; perhaps there were some problems with some older
GCC version (or this one, even; it's ancient as well).

Or, what does

/opt/crosstool/gcc-4.1.0-glibc-2.3.6/powerpc64-unknown-linux-gnu/ 4.1.0/
-name libgcov.a

say? (It should usually find three versions: 64-bit, 32-bit, 32-bit no

Only a single hit:

Right, as expected.

You *can* build with a non-biarch compiler, but then you need to point
the kernel build system at a 32-bit toolchain to use for the 32-bit
parts (via CROSS32_COMPILE).

Jens built this one, using crosstool. It is

It was all working happily until gcov came along :(

You were lucky, yes. If your compiler would have been just a little
bit older it wouldn't have been able to build 32-bit at all.

Do you have a separate 32-bit PowerPC compiler? If so, just set
CROSS32_COMPILE to it; if not, you'll need a new toolchain. In
that case, it's probably worthwhile to upgrade to 4.1.2 at least...


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