Date: Mon, 23 Apr 2012 17:32:24 +0800 From: Fengwei yin <yfw.bsd@gmail.com> To: Slawa Olhovchenkov <slw@zxy.spb.ru> Cc: jack.ren@intel.com, freebsd-threads@freebsd.org Subject: Re: About the memory barrier in BSD libc Message-ID: <CAPHpMu=kCwhf1RV_sYBDWDPL8368YTMLXge4L_g_F4AkTX1H5g@mail.gmail.com> In-Reply-To: <20120423084120.GD76983@zxy.spb.ru> References: <CAPHpMu=DOGQ=TuFeYH7bH8hVwteT4Q3k67-mvoOFob6P3Y506w@mail.gmail.com> <20120423084120.GD76983@zxy.spb.ru>
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On Mon, Apr 23, 2012 at 4:41 PM, Slawa Olhovchenkov <slw@zxy.spb.ru> wrote:
> On Mon, Apr 23, 2012 at 02:56:03PM +0800, Fengwei yin wrote:
>
>> Hi list,
>> If this is not correct question on the list, please let me know and
>> sorry for noise.
>>
>> I have a question regarding the BSD libc for SMP arch. I didn't see
>> memory barrier used in libc.
>> How can we make sure it's safe on SMP arch?
>
> /usr/include/machine/atomic.h:
>
> #define mb() =A0 =A0__asm __volatile("lock; addl $0,(%%esp)" : : : "memor=
y")
> #define wmb() =A0 __asm __volatile("lock; addl $0,(%%esp)" : : : "memory"=
)
> #define rmb() =A0 __asm __volatile("lock; addl $0,(%%esp)" : : : "memory"=
)
>
Thanks for the information. But it looks no body use it in libc.
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