Messages in this thread | | | Date | Wed, 01 Mar 2006 11:45:26 +0100 | From | Jes Sorensen <> | Subject | Re: [PATCH] Define wc_wmb, a write barrier for PCI write combining |
| |
Bryan O'Sullivan wrote: > On Tue, 2006-02-28 at 05:01 -0500, Jes Sorensen wrote: > > >>Could you explain why the current mmiowb() API won't suffice for this? >>It seems that this is basically trying to achieve the same thing. > > > It's a no-op on every arch I care about: > > #define mmiowb() > > Which makes it useless. Also, based on the comments in the qla driver, > mmiowb() seems to have inter-CPU ordering semantics that I don't want. > I'm thus hesitant to appropriate it for my needs.
The fact that it's a no-op may simply be because nobody on a specific arch got to the point where it made sense to define it yet.
Anyway, based on Jesse and Jeremy's comments, then maybe the semantics here are different. However I do think the name wc_wmb() isn't quite defining it. If it's only to be used on mmio space, something like mmio_wc_wmb() would probably be more descriptive.
Cheers, Jes - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |