Commit ae1b22f6 authored by Rusty Russell's avatar Rusty Russell Committed by Ingo Molnar

x86: Side-step lguest problem by only building cmpxchg8b_emu for pre-Pentium

Commit 79e1dd05 "x86: Provide an alternative() based
cmpxchg64()" broke lguest, even on systems which have cmpxchg8b
support.  The emulation code gets used until alternatives get
run, but it contains native instructions, not their paravirt
alternatives.

The simplest fix is to turn this code off except for 386 and 486
builds.
Reported-by: default avatarJohannes Stezenbach <js@sig21.net>
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
Acked-by: default avatarH. Peter Anvin <hpa@zytor.com>
Cc: lguest@ozlabs.org
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <200910261426.05769.rusty@rustcorp.com.au>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 14a3f40a
......@@ -400,7 +400,7 @@ config X86_TSC
config X86_CMPXCHG64
def_bool y
depends on X86_PAE || X86_64 || MCORE2 || MPENTIUM4 || MPENTIUMM || MPENTIUMIII || MPENTIUMII || M686 || MATOM
depends on !M386 && !M486
# this should be set for all -march=.. options where the compiler
# generates cmov.
......
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