[Xen-devel] tools/libxc/xc_cpuid_x86.c:cpuid()'s inline asm

["Jan Beulich" <JBeulich@xxxxxxxx>]

Keir,

do you recall what it was that 20976:f8692cc67d67 was supposed to fix?
The code is clearly wrong now on x86-64 - inline asm that uses push/pop
(or other stack pointer manipulation instructions) and memory accesses
that may reference the stack (even if not through %rsp) can't be
expected to work without -mno-red-zone.

The question is whether to use that command line option, or whether to
correct the inline assembly (besides the purpose of your change, I also
wonder why this isn't coded the obvious way, with rBX and rDX explicitly
named in the constraints - on 32-bit this may be to reduce register
pressure, but on 64-bit it's entirely unclear).

Thanks, Jan


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