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authorLinus Torvalds <torvalds@linux-foundation.org>2008-09-05 09:30:14 -0700
committerH. Peter Anvin <hpa@zytor.com>2008-09-08 11:35:43 -0700
commit14469a8dd23677921db5e7354a602c98d9c6300f (patch)
tree87aab243efb6dea0a8fb38fe6207764b24b82e6b
parent0253398ca1df7e1d2bfbb452175c964a0862482c (diff)
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 <hpa@zytor.com>
-rw-r--r--arch/x86/Kconfig.cpu13
1 files changed, 8 insertions, 5 deletions
diff --git a/arch/x86/Kconfig.cpu b/arch/x86/Kconfig.cpu
index 2c518fbc52ec..b225219c448c 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

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