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From: Peter Maydell <peter.maydell@linaro.org>
Date: Mon, 6 Jul 2015 11:04:24 +0100
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Subject: Re: [Qemu-devel] [PATCH] virtio-pci: implement cfg capability
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To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>, =?UTF-8?Q?Herv=C3=A9_Poussineau?= <hpoussin@reactos.org>, QEMU Developers <qemu-devel@nongnu.org>

On 6 July 2015 at 11:03, Michael S. Tsirkin <mst@redhat.com> wrote:
> On Mon, Jul 06, 2015 at 10:11:18AM +0100, Peter Maydell wrote:
>> But address_space_rw() is just the "memcpy bytes to the
>> target's memory" operation -- if you have a pile of bytes
>> then there are no endianness concerns. If you don't have
>> a pile of bytes then you need to know the structure of
>> the data you're DMAing around, and you should probably
>> have a loop doing things with the specify-the-width functions.

> Absolutely. But what if DMA happens to target another device
> and not memory? Device needs some endian-ness so it needs
> to be converted to that.

Yes, and address_space_rw() already deals with conversion to
that device's specified endianness.

-- PMM