Date: Wed, 22 Sep 2004 13:44:54 -0700 From: Marcel Moolenaar <marcel@xcllnt.net> To: Alan Cox <alc@cs.rice.edu> Cc: cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/ia64/include atomic.h Message-ID: <20040922204454.GA60053@alpha.pn.xcllnt.net> In-Reply-To: <20040922202210.GE16687@cs.rice.edu> References: <200409221958.i8MJwhEL060898@repoman.freebsd.org> <20040922202210.GE16687@cs.rice.edu>
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On Wed, Sep 22, 2004 at 03:22:10PM -0500, Alan Cox wrote:
> > 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.
>
> 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.)
Yes, it's probably a good idea to extend the set of atomic operations.
That way we have better consistency across platforms. For now (I didn't
want to embark on yet another cross-platform overhaul as the result of
wanting to improve ia64) I'm happy with it being an undocumented feature
on ia64 (ala sparc64).
In my WIP, I introduced pte_atomic_set() and pte_atomic_clear() to
avoid using the atomic functions directly, so if we later grow new
functions, it's easy for me to switch to them.
--
Marcel Moolenaar USPA: A-39004 marcel@xcllnt.net
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