linux-kernel - NOPL on 32-bit

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Message-ID: <20101003093701.GB3733@liondog.tnic>
Date:	Sun, 3 Oct 2010 11:37:01 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Ingo Molnar <mingo@...e.hu>, Thomas Gleixner <tglx@...utronix.de>,
	lkml <linux-kernel@...r.kernel.org>
Subject: NOPL on 32-bit

Hi,

it looks like we currently clear X86_FEATURE_NOPL in detect_nopl()
unconditionally and not only on 32-bit, as it should be according to
ba0593bf553c450a03dbc5f8c1f0ff58b778a0c8.

I'm thinking maybe something like the following might be in order

--
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index caa967d..9a2cfeb 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -713,7 +713,9 @@ void __init early_cpu_init(void)
  */
 static void __cpuinit detect_nopl(struct cpuinfo_x86 *c)
 {
+#ifdef CONFIG_X86_32
 	clear_cpu_cap(c, X86_FEATURE_NOPL);
+#endif
 }
 
 static void __cpuinit generic_identify(struct cpuinfo_x86 *c)
--

or maybe get even more radical and rip out the whole X86_FEATURE_NOPL
thing?

-- 
Regards/Gruss,
    Boris.
--
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