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Re: [Qemu-devel] virtio_tswaps() vs virtio_ld/st_p()
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From: |
Paolo Bonzini |
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Subject: |
Re: [Qemu-devel] virtio_tswaps() vs virtio_ld/st_p() |
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Date: |
Mon, 19 Jan 2015 14:01:07 +0100 |
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User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.3.0 |
On 19/01/2015 13:53, Peter Maydell wrote:
> > Heh, not sure I would have provided such a comprehensive answer. :)
>
> ...so now I have a question: what semantics does virtio expect
> for its virtio_ld*/st*_phys accessors if QEMU is emulating a
> CPU with virtualization support? Is the assumption just that
> the guest that's using virtio has a 1:1 mapping of what it
> thinks are physical addresses to real guest physical addresses?
Right now, the semantics are "PPC uses DMA addresses, everything else
uses physical addresses". However, this could be changed since x86
IOMMU support is still experimental, and without an IOMMU DMA addresses
_are_ physical addresses.
Paolo