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From: Cornelia Huck <cornelia.huck@de.ibm.com>
To: Jason Wang <jasowang@redhat.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>,
	qemu-devel@nongnu.org, "Michael S. Tsirkin" <mst@redhat.com>
Subject: Re: [Qemu-devel] [2.5 issue] virtio-1 in virtio-net and old vhost
Date: Fri, 4 Dec 2015 11:15:48 +0100	[thread overview]
Message-ID: <20151204111548.155ea5f7.cornelia.huck@de.ibm.com> (raw)
In-Reply-To: <5660F542.8010309@redhat.com>

On Fri, 4 Dec 2015 10:06:58 +0800
Jason Wang <jasowang@redhat.com> wrote:

> The problem is for pci: without this patch, guest may always see modern
> bar is "disable-modern=false". But with this patch, on an old kernel
> that does not support VERSION_1, even "disable-modern=false" were
> specified, guest can not see modern bar anymore. Looks like a guest
> visible change.

But the guest even see a modern bar if the host is not able to present
a spec-compliant device?

What we have now is a device that looks like a modern device but that
does not offer VERSION_1. Probably not spec compliant. If virtio-pci is
fixed to not present such broken devices to the guest, this is
guest-visible, yes; but only in the sense that the guest will no longer
see broken devices, but simply legacy devices if configured.

  reply	other threads:[~2015-12-04 10:16 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-12-01 10:11 [Qemu-devel] [2.5 issue] virtio-1 in virtio-net and old vhost Cornelia Huck
2015-12-01 12:10 ` Cornelia Huck
2015-12-01 14:21   ` Cornelia Huck
2015-12-02  5:54     ` Jason Wang
2015-12-02 10:11       ` Cornelia Huck
2015-12-02 12:41         ` Michael S. Tsirkin
2015-12-04  2:06         ` Jason Wang
2015-12-04 10:15           ` Cornelia Huck [this message]
2015-12-04 13:36             ` Michael S. Tsirkin

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