linux-kernel - Re: [PATCH RFC V4 09/10] x86/jump_label: use GENERIC_NOP5

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Message-ID: <4E9716B8.8050406@goop.org>
Date:	Thu, 13 Oct 2011 09:50:00 -0700
From:	Jeremy Fitzhardinge <jeremy@...p.org>
To:	"H. Peter Anvin" <hpa@...or.com>
CC:	Steven Rostedt <rostedt@...dmis.org>,
	"David S. Miller" <davem@...emloft.net>,
	David Daney <david.daney@...ium.com>,
	Michael Ellerman <michael@...erman.id.au>,
	Jan Glauber <jang@...ux.vnet.ibm.com>,
	Jason Baron <jbaron@...hat.com>,
	the arch/x86 maintainers <x86@...nel.org>,
	Xen Devel <xen-devel@...ts.xensource.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...e.hu>,
	Peter Zijlstra <peterz@...radead.org>,
	Jeremy Fitzhardinge <jeremy.fitzhardinge@...rix.com>
Subject: Re: [PATCH RFC V4 09/10] x86/jump_label: use GENERIC_NOP5_ATOMIC
 instead of jmp5 +0

On 10/13/2011 08:40 AM, H. Peter Anvin wrote:
> On 10/12/2011 05:08 PM, Jeremy Fitzhardinge wrote:
>> From: Jeremy Fitzhardinge <jeremy.fitzhardinge@...rix.com>
>>
>> GENERIC_NOP5_ATOMIC should make a better nop.
>>
> On 32 bits, yes.  On 64 bits you should use P6_NOP5_ATOMIC.

So the cleanest way of fixing that is to make the GENERIC_NOP*  be
defined to P6_NOP* on 64-bit then?  Assuming I'm correct in guessing
that the intent of GENERIC_NOP* is "a basically good-enough NOP that
will work on any x86".

    J
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