[Qemu-devel] Re: [PATCH 0/4] Block DMA helpers (v2)

[Avi Kivity <avi@redhat.com>]

Anthony Liguori wrote:
> BTW, what are your plans for virtio?  

To hope someone else does it.

> I'd reckon that just trying to map the full SG list and failing 
> gracefully if unable would be sufficient.  You could also convert the 
> element to contain a QEMUSGList and then make use of the IO helpers in 
> virtio-blk and virtio-net.  It just gets a little funky for simpler 
> things like virtio-console and virtio-balloon.

One way is to convert the generic transport layer to use two QEMUSGLists 
(one for incoming, one for outgoing) and leave it at that.  virtio-blk 
could use the block dma helpers, virtio-net could do something else, and 
we'd add a qemu_sglist_to_buffer(sg, offset, len, buf) and 
qemu_sglist_from_buffer(sg, offset, len, buf) to allow low-bandwidth 
easy access to virtio data.

This requires that the generic layer be able to tell where a request 
ends; don't know if that's the case now.

-- 
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.