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[Xen-devel] Re: [ofa-general] Re: mthca use of dma_sync_single is bogus
- To: "Michael S. Tsirkin" <mst@xxxxxxxxxxxxxxxxxx>
- From: Roland Dreier <rdreier@xxxxxxxxx>
- Date: Tue, 10 Jul 2007 11:09:01 -0700
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- Cc: Lukas Hejtmanek <xhejtman@xxxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxx, Keir Fraser <keir@xxxxxxxxxxxxx>, general@xxxxxxxxxxxxxxxxxxxxx
- Delivery-date: Tue, 17 Jul 2007 05:01:30 -0700
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- List-id: Xen developer discussion <xen-devel.lists.xensource.com>
> Aha. I looked at the code a bit.
> Basically is seems that some architectures use the dma handle
> and some the virtual address to flush the cache, that's
> where the requirement that same parameters are used for
> sync single as for map single comes from.
> So it seems that this requirement does not apply to s/g, and that we can just
> build a scatterlist structure and do dma_sync_sg?
synchronise a single contiguous or scatter/gather mapping. All the
parameters must be the same as those passed into the single mapping
in DMA-API.txt also is clearly attached to dma_sync_sg(). So I don't
think it's a good idea to rely on being able to sync a different
scatterlist than the one that was originally mapped.
It actually doesn't look too bad to replace our use of pci_map_sg()
with dma_map_single(), at least at first glance. I'll try to write a
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