From ae1b22f6e46c03cede7cea234d0bf2253b4261cf Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Mon, 26 Oct 2009 14:26:04 +1030 Subject: [PATCH] x86: Side-step lguest problem by only building cmpxchg8b_emu for pre-Pentium Commit 79e1dd05d1a22 "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: Johannes Stezenbach Signed-off-by: Rusty Russell Acked-by: H. Peter Anvin Cc: lguest@ozlabs.org Cc: Arjan van de Ven Cc: Jeremy Fitzhardinge Cc: Linus Torvalds LKML-Reference: <200910261426.05769.rusty@rustcorp.com.au> Signed-off-by: Ingo Molnar --- arch/x86/Kconfig.cpu | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/Kconfig.cpu b/arch/x86/Kconfig.cpu index f2824fb..2649840 100644 --- a/arch/x86/Kconfig.cpu +++ b/arch/x86/Kconfig.cpu @@ -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. -- 2.7.4