From: Paolo Bonzini <pbonzini@redhat.com>
To: Peter Maydell <peter.maydell@linaro.org>,
Greg Kurz <gkurz@linux.vnet.ibm.com>
Cc: Stefan Hajnoczi <stefanha@gmail.com>, qemu-devel <qemu-devel@nongnu.org>
Subject: Re: [Qemu-devel] virtio_tswaps() vs virtio_ld/st_p()
Date: Mon, 19 Jan 2015 14:01:07 +0100 [thread overview]
Message-ID: <54BD0013.5040201@redhat.com> (raw)
In-Reply-To: <CAFEAcA8GhX7quVksGOajz0Bq_vfR2duia+DdO9wtZmiGChJ7KA@mail.gmail.com>
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
next prev parent reply other threads:[~2015-01-19 13:01 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-19 11:35 [Qemu-devel] virtio_tswaps() vs virtio_ld/st_p() Stefan Hajnoczi
2015-01-19 11:45 ` Peter Maydell
2015-01-19 12:49 ` Greg Kurz
2015-01-19 12:53 ` Peter Maydell
2015-01-19 13:01 ` Paolo Bonzini [this message]
2015-01-19 13:10 ` Stefan Hajnoczi
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