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From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: Mon, 12 Aug 2013 19:56:39 +1000
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Subject: Re: [Qemu-devel] [PATCH 1/8] virtio_get_byteswap: function for
 endian-ambivalent targets using virtio.
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To: Peter Maydell <peter.maydell@linaro.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>, qemu-devel@nongnu.org

On Mon, 2013-08-12 at 10:52 +0100, Peter Maydell wrote:
> On 12 August 2013 10:50, Benjamin Herrenschmidt
> <benh@kernel.crashing.org> wrote:
> > I must be confused ... you mentioned in a previous discussion around
> > endianness that on some ARM cores at least, when changing the OS
> > endianness, you had to configure a different lane swapping in the bridge
> > to the the IO devices (AXI ?)
> 
> No, that's just the implementation -- the bit in the control
> register is effectively controlling whether there is byte lane
> swapping in the part of the CPU which is the data path between
> it and its bus to the outside world.

I find it amazing that an OS can touch that without hitting the
hypervisor :-) Anyway, ok, we do need to poll from virtio then, but we
probably need to cache as well, no ?

When do you sample it in qemu ?

Cheers,
Ben.