Re: [Qemu-devel] [PATCH 1/8] virtio_get_byteswap: function for endian-ambivalent targets using virtio.

[Rusty Russell <rusty@rustcorp.com.au>]

Alexander Graf <agraf@suse.de> writes:
> On 02/18/2014 05:17 PM, Cornelia Huck wrote:
>> Hm. So whatever_le for 1.0 devices, and virtio_whatever (checking the
>> byteswap value) for legacy devices? The device implementation will be
>> aware of the virtio version anyway.
>
> Yeah, but I would hope we want to share as much code as possible here, 
> so that config accessors can be shared between legacy virtio and 1.0 
> virtio. And in that case we want to have a generic helper to read/write 
> pieces of that config space - which this patch introduces for us :).
>
>> (Btw., can some of those architectures supporting both le/be run with
>> mixed le/be cpus? That would be a mess for legacy devices.)
>
> Yes, they can. No, we don't care :).

There's per-cpu (what endian) and per-device (legacy or no).  To do this
Right, we'd need to consult both, but we don't always have that
information.  So this the minimal viable solution.

We'll need a per-device legacy flag eventually (there are other changes
than just endian).  But getting the wrappers in place is a good first
step.

Cheers,
Rusty.