From: Linus Torvalds Date: Fri, 5 Sep 2008 16:30:14 +0000 (-0700) Subject: x86: disable static NOPLs on 32 bits X-Git-Tag: v2.6.27-rc6~4^2~1 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=14469a8dd23677921db5e7354a602c98d9c6300f;p=linux-2.6 x86: disable static NOPLs on 32 bits On 32-bit, at least the generic nops are fairly reasonable, but the default nops for 64-bit really look pretty sad, and the P6 nops really do look better. So I would suggest perhaps moving the static P6 nop selection into the CONFIG_X86_64 thing. The alternative is to just get rid of that static nop selection, and just have two cases: 32-bit and 64-bit, and just pick obviously safe cases for them. Signed-off-by: H. Peter Anvin --- diff --git a/arch/x86/Kconfig.cpu b/arch/x86/Kconfig.cpu index 2c518fbc52..b225219c44 100644 --- a/arch/x86/Kconfig.cpu +++ b/arch/x86/Kconfig.cpu @@ -382,14 +382,17 @@ config X86_OOSTORE # P6_NOPs are a relatively minor optimization that require a family >= # 6 processor, except that it is broken on certain VIA chips. # Furthermore, AMD chips prefer a totally different sequence of NOPs -# (which work on all CPUs). As a result, disallow these if we're -# compiling X86_GENERIC but not X86_64 (these NOPs do work on all -# x86-64 capable chips); the list of processors in the right-hand clause -# are the cores that benefit from this optimization. +# (which work on all CPUs). In addition, it looks like Virtual PC +# does not understand them. +# +# As a result, disallow these if we're not compiling for X86_64 (these +# NOPs do work on all x86-64 capable chips); the list of processors in +# the right-hand clause are the cores that benefit from this optimization. # config X86_P6_NOP def_bool y - depends on (X86_64 || !X86_GENERIC) && (M686 || MPENTIUMII || MPENTIUMIII || MPENTIUMM || MCORE2 || MPENTIUM4 || MPSC) + depends on X86_64 + depends on (MCORE2 || MPENTIUM4 || MPSC) config X86_TSC def_bool y