From: Rusty Russell <rusty@rustcorp.com.au>
To: "Michael S. Tsirkin" <mst@redhat.com>, linux-kernel@vger.kernel.org
Cc: Cornelia Huck <cornelia.huck@de.ibm.com>, Pawel Moll <pawel.moll@arm.com>,
        virtio-dev@lists.oasis-open.org,
        virtualization@lists.linux-foundation.org
Subject: Re: [PATCH v3 0/6] virtio_balloon: virtio 1 support
In-Reply-To: <20150412170141-mutt-send-email-mst@redhat.com>
References: <1427884468-23930-1-git-send-email-mst@redhat.com> <20150412170141-mutt-send-email-mst@redhat.com>
User-Agent: Notmuch/0.17 (http://notmuchmail.org) Emacs/24.3.1 (x86_64-pc-linux-gnu)
Date: Tue, 14 Apr 2015 10:42:56 +0930
Message-ID: <87h9sjtsvb.fsf@rustcorp.com.au>
MIME-Version: 1.0
Content-Type: text/plain
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1652
Lines: 35

"Michael S. Tsirkin" <mst@redhat.com> writes:
> On Wed, Apr 01, 2015 at 02:57:35PM +0200, Michael S. Tsirkin wrote:
>> Virtio 1.0 doesn't include a modern balloon device.  At some point we'll likely
>> define an incompatible interface with a different ID and different
>> semantics.  But for now, it's not a big effort to support a transitional
>> balloon device: this has the advantage of supporting existing drivers,
>> transparently, as well as transports that don't allow mixing virtio 0 and
>> virtio 1 devices. And balloon is an easy device to test, so it's also useful
>> for people to test virtio core handling of transitional devices.
>> 
>> The only interface issue is with the stats buffer, which has misaligned
>> fields. We could leave it as is, but this sets a bad precedent that
>> others might copy by mistake.
>> 
>> As we need to change stats code to do byteswaps for virtio 1.0, it seems easy
>> to fix by prepending a 6 byte reserved field.  I also had to change config
>> structure field types from __le32 to __u32 to match other devices. This means
>> we need a couple of __force tags for legacy path but that seems minor.
>
> Rusty, what are your thoughts here?
> How about merging this for 4.1?

I disagree with making any changes, other than allowing it to be used
with VIRTIO_F_VERSION_1.

However it doesn't seem to bother anyone else, so I've applied it for
4.1.

Thanks,
Rusty.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/