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Gcc-4.6 breaks kernel builds



Hi,

tl;dr if something inexplicably fails, try recompiling with gcc-4.7

I recently encountered problems with kernels compiled from Lemote's
"official" Loongson-3A branch [1].  Turns out that these problems are
only present if I compile the kernel with gcc-4.6.  I tested with the
gcc-4.6.3 that comes with Debian Wheezy mipsel, and also with a
self-made amd64->mips cross-toolchain built from gcc-4.6.4 sources.
Kernels built from both toolchains exhibit the same problem (blank
screen approx. 1 minute after boot).  I desperately compiled a lot of
different versions with different options of these loongson-3a kernels,
but non worked (using these compilers).

Switching to a gcc 4.5 or 4.7 series compiler in all cases fixed the
problem: Tested with Debian Wheezy mipsel's 4.7 compiler as well as with
cross-compilers built from gcc 4.7.3 and gcc 4.5.4 sources and Lemote's
binary 4.5.2 cross toolchain [2].

Of course it may still not be GCC's fault; could be a problem with
Lemote's kernel or CPU that only shows when compiled with the "right"
toolchain.

cheers,

David

[1] http://dev.lemote.com/cgit/linux-official.gi
[2] http://dev.lemote.com/files/resource/toolchain/cross-compile/
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