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Re: [Qemu-devel] [virtio-dev] RE: [PATCH v3 6/6] vhost-user: support reg
From: |
Michael S. Tsirkin |
Subject: |
Re: [Qemu-devel] [virtio-dev] RE: [PATCH v3 6/6] vhost-user: support registering external host notifiers |
Date: |
Thu, 19 Apr 2018 19:48:55 +0300 |
On Thu, Apr 19, 2018 at 06:07:07PM +0200, Paolo Bonzini wrote:
> On 19/04/2018 17:59, Michael S. Tsirkin wrote:
> > On Thu, Apr 19, 2018 at 05:51:51PM +0200, Paolo Bonzini wrote:
> >> On 19/04/2018 17:19, Michael S. Tsirkin wrote:
> >>>> - if we make it 1 when weak barriers are needed, the device also needs
> >>>> to nack feature negotiation (not allow setting the FEATURES_OK) if the
> >>>> bit is not set by the driver.
> >>>> However, that is not enough. Live
> >>>> migration assumes that it is okay to migrate a virtual machine from a
> >>>> source that doesn't support a feature to a destination that supports it.
> >>>> In this case, it would assume that it is okay to migrate from software
> >>>> virtio to hardware virtio. This is wrong because the destination would
> >>>> use weak barriers
> >>>
> >>> You can't migrate between systems with different sets of device features
> >>> right now.
> >>
> >> Yes, you can, exactly because some features are defined not by the
> >> machine type but rather by the host kernel. See virtio_net_get_features
> >> in QEMU's hw/virtio/virtio-net.c, and virtio_set_features_nocheck in
> >> QEMU's hw/virtio/virtio.c.
> >
> > Oh you are right. Well we can just special-case that one :)
>
> Anything wrong with bumping the PCI revision?
>
> Paolo
Nothing except in virtio 1 bumping the revision does not prevent
loading the old driver.
--
MST
- [Qemu-devel] [PATCH v3 5/6] vhost: allow backends to filter memory sections, (continued)
- [Qemu-devel] [PATCH v3 5/6] vhost: allow backends to filter memory sections, Tiwei Bie, 2018/04/12
- [Qemu-devel] [PATCH v3 6/6] vhost-user: support registering external host notifiers, Tiwei Bie, 2018/04/12
- Re: [Qemu-devel] [PATCH v3 6/6] vhost-user: support registering external host notifiers, Michael S. Tsirkin, 2018/04/18
- Re: [Qemu-devel] [PATCH v3 6/6] vhost-user: support registering external host notifiers, Tiwei Bie, 2018/04/19
- Re: [Qemu-devel] [PATCH v3 6/6] vhost-user: support registering external host notifiers, Liang, Cunming, 2018/04/19
- Re: [Qemu-devel] [virtio-dev] RE: [PATCH v3 6/6] vhost-user: support registering external host notifiers, Paolo Bonzini, 2018/04/19
- Re: [Qemu-devel] [virtio-dev] RE: [PATCH v3 6/6] vhost-user: support registering external host notifiers, Michael S. Tsirkin, 2018/04/19
- Re: [Qemu-devel] [virtio-dev] RE: [PATCH v3 6/6] vhost-user: support registering external host notifiers, Paolo Bonzini, 2018/04/19
- Re: [Qemu-devel] [virtio-dev] RE: [PATCH v3 6/6] vhost-user: support registering external host notifiers, Michael S. Tsirkin, 2018/04/19
- Re: [Qemu-devel] [virtio-dev] RE: [PATCH v3 6/6] vhost-user: support registering external host notifiers, Paolo Bonzini, 2018/04/19
- Re: [Qemu-devel] [virtio-dev] RE: [PATCH v3 6/6] vhost-user: support registering external host notifiers,
Michael S. Tsirkin <=
- Re: [Qemu-devel] [virtio-dev] RE: [PATCH v3 6/6] vhost-user: support registering external host notifiers, Liang, Cunming, 2018/04/19
- Re: [Qemu-devel] [virtio-dev] RE: [PATCH v3 6/6] vhost-user: support registering external host notifiers, Michael S. Tsirkin, 2018/04/19
- Re: [Qemu-devel] [virtio-dev] RE: [PATCH v3 6/6] vhost-user: support registering external host notifiers, Liang, Cunming, 2018/04/19
- Re: [Qemu-devel] [PATCH v3 6/6] vhost-user: support registering external host notifiers, Michael S. Tsirkin, 2018/04/19
- Re: [Qemu-devel] [PATCH v3 6/6] vhost-user: support registering external host notifiers, Paolo Bonzini, 2018/04/19
- Re: [Qemu-devel] [PATCH v3 6/6] vhost-user: support registering external host notifiers, Michael S. Tsirkin, 2018/04/19
- Re: [Qemu-devel] [PATCH v3 6/6] vhost-user: support registering external host notifiers, Liang, Cunming, 2018/04/19
- Re: [Qemu-devel] [virtio-dev] RE: [PATCH v3 6/6] vhost-user: support registering external host notifiers, Paolo Bonzini, 2018/04/19
- Re: [Qemu-devel] [virtio-dev] RE: [PATCH v3 6/6] vhost-user: support registering external host notifiers, Michael S. Tsirkin, 2018/04/19
- Re: [Qemu-devel] [virtio-dev] RE: [PATCH v3 6/6] vhost-user: support registering external host notifiers, Paolo Bonzini, 2018/04/19