From mboxrd@z Thu Jan  1 00:00:00 1970
From: Rusty Russell <rusty@rustcorp.com.au>
Subject: Re: [RFC 7/11] virtio_pci: new, capability-aware driver.
Date: Thu, 12 Jan 2012 12:05:06 +1030
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To: Anthony Liguori <anthony@codemonkey.ws>
Cc: Pawel Moll <pawel.moll@arm.com>, "Michael S. Tsirkin" <mst@redhat.com>, Benjamin Herrenschmidt <benh@kernel.crashing.org>, virtualization <virtualization@lists.linux-foundation.org>, Christian Borntraeger <borntraeger@de.ibm.com>, Sasha Levin <levinsasha928@gmail.com>
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On Wed, 11 Jan 2012 07:30:34 -0600, Anthony Liguori <anthony@codemonkey.ws> wrote:
> I think the more important thing to do is require accesses to integers in the 
> config space to always be aligned and to use the appropriate accessor. 
> Non-integer fields should be restricted to byte access.
> 
> That limits config space entries to 32-bit but also means that there is no need 
> for a generation counter.

Unfortunately not, see virtio_blk.  capacity is 64 bits, and geometry is
multiple fields.

> If we're already making the change, the endianness ought to be a feature bit.

I'd rather tie it to the new PCI config layout (and ring format).  Then
we can simply have two backends, legacy and modern.

For non-PCI, we would need a feature bit.

Cheers,
Rusty.