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Re: [Qemu-devel] [virtio-dev] RE: [PATCH v3 6/6] vhost-user: support reg
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [virtio-dev] RE: [PATCH v3 6/6] vhost-user: support registering external host notifiers |
Date: |
Thu, 19 Apr 2018 17:51:51 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 |
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.
Thanks,
Paolo
- [Qemu-devel] [PATCH v3 2/6] vhost-user: introduce shared vhost-user state, (continued)
- [Qemu-devel] [PATCH v3 2/6] vhost-user: introduce shared vhost-user state, Tiwei Bie, 2018/04/12
- [Qemu-devel] [PATCH v3 3/6] vhost-user: support receiving file descriptors in slave_read, Tiwei Bie, 2018/04/12
- [Qemu-devel] [PATCH v3 4/6] virtio: support setting memory region based host notifier, Tiwei Bie, 2018/04/12
- [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 <=
- 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, 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