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From: Rusty Russell <rusty@rustcorp.com.au>
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Date: Tue, 13 Aug 2013 13:50:05 +0930
Message-ID: <87a9kmmdca.fsf@rustcorp.com.au>
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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: Anthony Liguori <anthony@codemonkey.ws>, Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: qemu-devel@nongnu.org

Anthony Liguori <anthony@codemonkey.ws> writes:
> Benjamin Herrenschmidt <benh@kernel.crashing.org> writes:
>
>> On Mon, 2013-08-12 at 17:29 +0930, Rusty Russell wrote:
>>> virtio data structures are defined as "target endian", which assumes
>>> that's a fixed value.  In fact, that actually means it's
>>> platform-specific.
>>> 
>>> Hopefully the OASIS virtio 1.0 spec will fix this.  Meanwhile, create
>>> a hook for little endian ppc.
>>
>> Ok, sorry if I missed a previous debate on that one but why do you do a
>> call-out to architecture specific stuff (that is not even inline) on
>> every access ?

Anthony said he wanted it that way: my initial patch was more optimized.

> Let's focus on getting something merged.  Then we can muck around with
> it down the road.
>
> Having target-ppc call into virtio is a layering violation.  This
> approach keeps the dependencies cleaner.

We can have it call once (eg. when the first and storing the status
word) and store the result.

Cheers,
Rusty.