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[Xen-devel] kexec woes with 32-bit secondary kernel

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Subject: [Xen-devel] kexec woes with 32-bit secondary kernel
From: "Jan Beulich" <JBeulich@xxxxxxxxxx>
Date: Fri, 17 Sep 2010 16:49:38 +0100
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Ever since c/s 13829, the native (32-bit -> 32-bit) call to invoke the
secondary kernel has been missing its fourth argument. Apparently
this worked out because the respective stack location was non-zero.

Starting with Linux 2.6.27 (32-bit) and 2.6.30 (64-bit) a new
argument is being expected by the secondary kernel, and again
apparently out of pure luck the 64-bit -> 64-bit case still appears
to work for those of our customers who want to use it.

The question really is whether this code has ever been tested
with sufficiently recent kernels in all three variants (32->32, 64->64,
and 64->32).

While it seems that putting together a patch to address this
shouldn't be that difficult, a second question is how we can avoid
getting into the same situation again when Linux extends the
protocol again.

Thanks, Jan

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