Re: [PATCH 2/3] dma: override "dma_flags_set_dmaflush" for sn-ia64

[Jes Sorensen]

James Bottomley wrote:
> On Tue, 2007-08-21 at 17:34 -0700, akepner@xxxxxxx wrote:
> > The term "posted DMA" is used to describe this behavior in the Altix 
> > Device Driver Writer's Guide, but it may be confusing things here. 
> > Maybe a better term will suggest itself if I can clarify....
>
> OK, but posted DMA has a pretty specific meaning in terms of PCI, hence
> the confusion.

Maybe it would be more better to refer to this as 'out of order DMA'?

> > On Altix, DMA from a device isn't guaranteed to arrive in host memory 
> > in the order it was sent from the device. This reordering can happen 
> > in the NUMA interconnect (it's specifically not a PCI reordering.)
>
> This is mmiowb and read_relaxed() again, isn't it?

I believe it's the same problem, except this time it's when exposing
structures to userland.

Cheers,
Jes
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