Date: Wed, 22 Sep 2004 15:22:10 -0500 From: Alan Cox <alc@cs.rice.edu> To: Marcel Moolenaar <marcel@FreeBSD.org> Cc: cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/ia64/include atomic.h Message-ID: <20040922202210.GE16687@cs.rice.edu> In-Reply-To: <200409221958.i8MJwhEL060898@repoman.freebsd.org> References: <200409221958.i8MJwhEL060898@repoman.freebsd.org>
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On Wed, Sep 22, 2004 at 07:58:43PM +0000, Marcel Moolenaar wrote:
> marcel 2004-09-22 19:58:43 UTC
>
> FreeBSD src repository
>
> Modified files:
> sys/ia64/include atomic.h
> Log:
> For the atomic_{add|clear|set|subtract} family of inlines, return the
> old or previous value instead of void. This is not as is documented
> in atomic(9), but is API (and ABI) compatible and simply makes sense.
> This feature will primarily be used for atomic PTE updates in PMAP/ng.
>
> Revision Changes Path
> 1.8 +4 -2 src/sys/ia64/include/atomic.h
Indeed, this is useful. There is precedent for this on sparc64. That said,
I have to admit that the inconsistency left me scratching my head for a few
minutes when I first read the sparc64 pmap.
It might be wise to come up with a different set of names for this variant.
On ia64 and sparc64, they could have the same implementation. (Whereas,
amd64 and i386 would probably have different implementations.)
Regards,
Alan
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