linux-kernel - Re: [PATCH] x86: Extend test_and_set_bit() test_and_clean_bit() to 64 bits in X86

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Message-Id: <200905141145.05591.sheng@linux.intel.com>
Date:	Thu, 14 May 2009 11:45:05 +0800
From:	Sheng Yang <sheng@...ux.intel.com>
To:	Andi Kleen <andi@...stfloor.org>
Cc:	linux-kernel@...r.kernel.org, "linux-mm" <linux-mm@...ck.org>,
	Ingo Molnar <mingo@...e.hu>, "H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH] x86: Extend test_and_set_bit() test_and_clean_bit() to 64 bits in X86_64

On Wednesday 13 May 2009 16:38:29 Andi Kleen wrote:
> Sheng Yang <sheng@...ux.intel.com> writes:
> > -static inline int test_and_set_bit(int nr, volatile unsigned long *addr)
> > +static inline int test_and_set_bit(long int nr, volatile unsigned long
> > *addr) {
> >  	int oldbit;
> >
> > -	asm volatile(LOCK_PREFIX "bts %2,%1\n\t"
> > +	asm volatile(LOCK_PREFIX REX_X86 "bts %2,%1\n\t"
>
> Use btsq on 64bit, then you don't need the explicit rex prefix.

Hi Andi

Well, I just think lots of "#ifdef/#else" is a little annoying here, then use 
REX...

-- 
regards
Yang, Sheng
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