Re: [PATCH v2 1/5] virtio: add functions for piecewise addition ofbuffers

[Paolo Bonzini]

Il 08/01/2013 01:12, Rusty Russell ha scritto:
>>>> >>> Unfortunately, that cannot work because not all architectures support
>>>> >>> chained scatterlists.
>>> >> 
>>> >> WHAT?  I can't figure out what an arch needs to do to support this?
>> >
>> > It needs to use the iterator functions in its DMA driver.
> But we don't care for virtio.

True.

>>> >> All archs we care about support them, though, so I think we can ignore
>>> >> this issue for now.
>> >
>> > Kind of... In principle all QEMU-supported arches can use virtio, and
>> > the speedup can be quite useful.  And there is no Kconfig symbol for SG
>> > chains that I can use to disable virtio-scsi on unsupported arches. :/
> Well, we #error if it's not supported.  Then the lazy architectures can
> fix it.

Yeah, that would be one approach.

But frankly, your patch is really disgusting. :)  Not your fault, of
course, but I still prefer a limited amount of duplication.

Perhaps we can get the best of both worlds, I'll take a look when I have
some time.

Paolo
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