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Date:      Mon, 08 Oct 2001 14:02:12 -0700 (PDT)
From:      John Baldwin <jhb@FreeBSD.org>
To:        John Baldwin <jhb@FreeBSD.org>
Cc:        cvs-all@FreeBSD.org, cvs-committers@FreeBSD.org
Subject:   RE: cvs commit: src/sys/i386/include atomic.h
Message-ID:  <XFMail.011008140212.jhb@FreeBSD.org>
In-Reply-To: <200110082058.f98KwPp88784@freefall.freebsd.org>

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On 08-Oct-01 John Baldwin wrote:
> jhb         2001/10/08 13:58:25 PDT
> 
>   Modified files:
>     sys/i386/include     atomic.h 
>   Log:
>   Allow atomic ops to be somewhat safely used in userland.  We always use
>   lock prefixes in the userland case so that the binaries will work on both
>   SMP and UP systems.

atomic_cmpset(), atomic_store(), and atomic_load() are still problematic as
there are 386 versions which are not SMP safe and non-386 versions which are
SMP safe.  A userland sourc file that uses atomic ops on x86 will have to
define I386_CPU if it wishes to compile the 386 versions, otherwise it will use
the 486+ and SMP safe versions.  This just means that if any userland
applications (such as possibly the new KSE thread library) use these atomic
ops, it will have to have separate versions for 386's and everything else in
the x86 family.

-- 

John Baldwin <jhb@FreeBSD.org> -- http://www.FreeBSD.org/~jhb/
PGP Key: http://www.baldwin.cx/~john/pgpkey.asc
"Power Users Use the Power to Serve!"  -  http://www.FreeBSD.org/

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