Re: [Xen-devel] General protection fault in netback

["Jan Beulich" <jbeulich@xxxxxxxx>]

>>> Anton Samsonov <avscomputing@xxxxxxxxx> 02/22/12 11:46 PM >>>
>As an example of the latter, look again at the Novell BZ #727081 mentioned
>in the original post â the comment #30 says: "The compiler apparently makes use
>of the 128-byte area called 'red zone' in the ABI, and this is incompatible
>with xc_cpuid_x86.c:cpuid() using pushes and pops around the cpuid 
>instruction".
>The consequence is that, on some machines, libxenguest segfaults when you
>try to start a DomU. With Core i7-920 there is no problem, but with Core 
>i5-2300
>I faced that issue, and wonder whether the same incompatibility can take place
>in netback module. I though the traceback gives some hints on where to debug.

That's impossible - use of the red zone is disallowed in the kernel via compiler
option. And the problem you cite was a source code problem, not a compiler
one (the fact that it had an effect only on some systems was attributed to the
function in question only getting run when a specific hardware feature was
available iirc).

Jan


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