| Message ID | 20120320062020.12815.61342.stgit@jason-ThinkPad-T400 |
|---|---|
| State | New |
| Headers | show |
On Tue, 20 Mar 2012 14:20:21 +0800, Jason Wang <jasowang@redhat.com> wrote: > This patch clarifies VIRTIO_NET_S_LINK_UP as a read-only bit and > VIRTIO_NET_S_ANNOUNCE as a read-writable bit. Also introduce the write 1 to > clear semantics for all read-writable bits of config status field. This could > help to reduce the config status field updating race between host and guest and > also simplify the implementation. > > Signed-off-by: Jason Wang <jasowang@redhat.com> This approach assumes an active config field, which neither lguest nor S/390 have. Thanks, Rusty.
On Tue, Mar 20, 2012 at 09:35:18PM +1030, Rusty Russell wrote: > On Tue, 20 Mar 2012 14:20:21 +0800, Jason Wang <jasowang@redhat.com> wrote: > > This patch clarifies VIRTIO_NET_S_LINK_UP as a read-only bit and > > VIRTIO_NET_S_ANNOUNCE as a read-writable bit. Also introduce the write 1 to > > clear semantics for all read-writable bits of config status field. This could > > help to reduce the config status field updating race between host and guest and > > also simplify the implementation. > > > > Signed-off-by: Jason Wang <jasowang@redhat.com> > > This approach assumes an active config field, which neither lguest nor > S/390 have. > > Thanks, > Rusty. What does 'active' mean in this context? > -- > How could I marry someone with more hair than me? http://baldalex.org
On Wed, 21 Mar 2012 00:48:05 +0200, "Michael S. Tsirkin" <mst@redhat.com> wrote: > On Tue, Mar 20, 2012 at 09:35:18PM +1030, Rusty Russell wrote: > > On Tue, 20 Mar 2012 14:20:21 +0800, Jason Wang <jasowang@redhat.com> wrote: > > > This patch clarifies VIRTIO_NET_S_LINK_UP as a read-only bit and > > > VIRTIO_NET_S_ANNOUNCE as a read-writable bit. Also introduce the write 1 to > > > clear semantics for all read-writable bits of config status field. This could > > > help to reduce the config status field updating race between host and guest and > > > also simplify the implementation. > > > > > > Signed-off-by: Jason Wang <jasowang@redhat.com> > > > > This approach assumes an active config field, which neither lguest nor > > S/390 have. > > > > Thanks, > > Rusty. > > What does 'active' mean in this context? It means you are assuming that writes to the config field trap to the host. Rusty.
On Wed, Mar 21, 2012 at 10:10:52AM +1030, Rusty Russell wrote: > On Wed, 21 Mar 2012 00:48:05 +0200, "Michael S. Tsirkin" <mst@redhat.com> wrote: > > On Tue, Mar 20, 2012 at 09:35:18PM +1030, Rusty Russell wrote: > > > On Tue, 20 Mar 2012 14:20:21 +0800, Jason Wang <jasowang@redhat.com> wrote: > > > > This patch clarifies VIRTIO_NET_S_LINK_UP as a read-only bit and > > > > VIRTIO_NET_S_ANNOUNCE as a read-writable bit. Also introduce the write 1 to > > > > clear semantics for all read-writable bits of config status field. This could > > > > help to reduce the config status field updating race between host and guest and > > > > also simplify the implementation. > > > > > > > > Signed-off-by: Jason Wang <jasowang@redhat.com> > > > > > > This approach assumes an active config field, which neither lguest nor > > > S/390 have. > > > > > > Thanks, > > > Rusty. > > > > What does 'active' mean in this context? > > It means you are assuming that writes to the config field trap to the > host. > > Rusty. Ah. Right, we need to trap for host to clear the bit. OK, so let's make the bit RO, and add VIRTIO_NET_CTRL_ANNOUNCED to acknowledge that we've seen VIRTIO_NET_S_ANNOUNCE using the control VQ? If there's no ctrl VQ, we won't acknowledge the feature bit ... > -- > How could I marry someone with more hair than me? http://baldalex.org
On Wed, 21 Mar 2012 08:37:46 +0200, "Michael S. Tsirkin" <mst@redhat.com> wrote: > Ah. Right, we need to trap for host to clear the bit. > OK, so let's make the bit RO, and add > VIRTIO_NET_CTRL_ANNOUNCED to acknowledge that we've > seen VIRTIO_NET_S_ANNOUNCE using the control VQ? Thanks, that's nice. Guest should send arp packets first, then send VIRTIO_NET_CTRL_ANNOUNCED, and ignore the bit being set in the meantime. Thanks, Rusty.
On 03/22/2012 12:30 PM, Rusty Russell wrote: > On Wed, 21 Mar 2012 08:37:46 +0200, "Michael S. Tsirkin"<mst@redhat.com> wrote: >> Ah. Right, we need to trap for host to clear the bit. >> OK, so let's make the bit RO, and add >> VIRTIO_NET_CTRL_ANNOUNCED to acknowledge that we've >> seen VIRTIO_NET_S_ANNOUNCE using the control VQ? > Thanks, that's nice. Guest should send arp packets first, then send > VIRTIO_NET_CTRL_ANNOUNCED, and ignore the bit being set in the meantime. > > Thanks, > Rusty. Sure, I would update and re-send the spec updating patch. Thanks
diff --git a/virtio-0.9.4.lyx b/virtio-0.9.4.lyx index 6c7bab1..614ab55 100644 --- a/virtio-0.9.4.lyx +++ b/virtio-0.9.4.lyx @@ -58,6 +58,7 @@ \html_be_strict false \author -608949062 "Rusty Russell,,," \author 1531152142 "pbonzini" +\author 2090695081 "jason" \end_header \begin_body @@ -4013,7 +4014,21 @@ layout Two configuration fields are currently defined. The mac address field always exists (though is only valid if VIRTIO_NET_F_MAC is set), and the status field only exists if VIRTIO_NET_F_STATUS is set. Two bits are currently defined for the status field: VIRTIO_NET_S_LINK_UP - and VIRTIO_NET_S_ANNOUNCE. + +\change_inserted 2090695081 1332220873 +(read-only) +\change_unchanged +and VIRTIO_NET_S_ANNOUNCE +\change_inserted 2090695081 1332220883 + (read-writable) +\change_unchanged +. + +\change_inserted 2090695081 1332220901 + Writing 1 to any read-writable bit of status filed would cause the bit + to be cleared. + +\change_unchanged \begin_inset listings inline false @@ -4915,7 +4930,11 @@ Processing this notification involves: \end_layout \begin_layout Enumerate -Clearing VIRTIO_NET_S_ANNOUNCE bit in the status field. +Clearing VIRTIO_NET_S_ANNOUNCE bit in the status field +\change_inserted 2090695081 1332220849 + (by writing 1 to VIRTIO_NET_S_ANNOUNCE bit) +\change_unchanged +. \end_layout \begin_layout Enumerate
This patch clarifies VIRTIO_NET_S_LINK_UP as a read-only bit and VIRTIO_NET_S_ANNOUNCE as a read-writable bit. Also introduce the write 1 to clear semantics for all read-writable bits of config status field. This could help to reduce the config status field updating race between host and guest and also simplify the implementation. Signed-off-by: Jason Wang <jasowang@redhat.com> --- virtio-0.9.4.lyx | 23 +++++++++++++++++++++-- 1 files changed, 21 insertions(+), 2 deletions(-)