linux-kernel - Re: [PATCH] x86: Create clflush() inline, remove hardcoded wbinvd

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Message-ID: <20070722042057.GJ1193@rhun.ibm.com>
Date:	Sun, 22 Jul 2007 07:20:57 +0300
From:	Muli Ben-Yehuda <muli@...ibm.com>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Andi Kleen <andi@...stfloor.org>,
	Glauber de Oliveira Costa <gcosta@...hat.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86: Create clflush() inline, remove hardcoded wbinvd

On Sat, Jul 21, 2007 at 03:09:41PM -0700, H. Peter Anvin wrote:
> Muli Ben-Yehuda wrote:
> > 
> > Ok, let's try again:
> > 
> > You're changing this (pageattr.c)
> > 
> >                 asm volatile("clflush (%0)" :: "r" (adr + i));
> > 
> > into this:
> > 
> > 		asm volatile("clflush %0" : "+m" (*(char __force*)(adr + i)));
> > 
> > The original one calls clflush with (adr + i), the new one with (*(adr
> > + i)). Are these calls equivalent?
> 
> Yes, they are.  The parentheses which are part of the old assembly
> string has the same effect as the asterisk operator in C.

Ah, I see. Thanks for the explanation!

Cheers,
Muli
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