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| author | Peter Maydell <peter.maydell@linaro.org> | 2019-07-25 16:38:24 +0100 |
|---|---|---|
| committer | Peter Maydell <peter.maydell@linaro.org> | 2019-07-25 16:38:24 +0100 |
| commit | 61c1e6a97deac9d5f9748ac1fa4e31e84e19f55c (patch) | |
| tree | ed6f14dafa833a7af15d3128ca1cfed6cd07f11a /docs | |
| parent | b43bea01b853dfdb6c0418615b57d0e1b98e9e98 (diff) | |
| parent | 1b47b37c33ec01ae1efc527f4c97f97f93723bc4 (diff) | |
| download | qemu-61c1e6a97deac9d5f9748ac1fa4e31e84e19f55c.zip qemu-61c1e6a97deac9d5f9748ac1fa4e31e84e19f55c.tar.gz qemu-61c1e6a97deac9d5f9748ac1fa4e31e84e19f55c.tar.bz2 | |
Merge remote-tracking branch 'remotes/mst/tags/for_upstream' into staging
virtio, pc: fixes, cleanups
A bunch of fixes all over the place.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
# gpg: Signature made Thu 25 Jul 2019 16:19:33 BST
# gpg: using RSA key 281F0DB8D28D5469
# gpg: Good signature from "Michael S. Tsirkin <mst@kernel.org>" [full]
# gpg: aka "Michael S. Tsirkin <mst@redhat.com>" [full]
# Primary key fingerprint: 0270 606B 6F3C DF3D 0B17 0970 C350 3912 AFBE 8E67
# Subkey fingerprint: 5D09 FD08 71C8 F85B 94CA 8A0D 281F 0DB8 D28D 5469
* remotes/mst/tags/for_upstream:
virtio-balloon: free pbp more aggressively
virtio-balloon: don't track subpages for the PBP
virtio-balloon: Use temporary PBP only
virtio-balloon: Rework pbp tracking data
virtio-balloon: Better names for offset variables in inflate/deflate code
virtio-balloon: Simplify deflate with pbp
virtio-balloon: Fix QEMU crashes on pagesize > BALLOON_PAGE_SIZE
virtio-balloon: Fix wrong sign extension of PFNs
i386/acpi: show PCI Express bus on pxb-pcie expanders
ioapic: kvm: Skip route updates for masked pins
i386/acpi: fix gint overflow in crs_range_compare
docs: clarify multiqueue vs multiple virtqueues
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Diffstat (limited to 'docs')
| -rw-r--r-- | docs/interop/vhost-user.rst | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/docs/interop/vhost-user.rst b/docs/interop/vhost-user.rst index 5750668..7827b71 100644 --- a/docs/interop/vhost-user.rst +++ b/docs/interop/vhost-user.rst @@ -324,6 +324,15 @@ must support changing some configuration aspects on the fly. Multiple queue support ---------------------- +Many devices have a fixed number of virtqueues. In this case the master +already knows the number of available virtqueues without communicating with the +slave. + +Some devices do not have a fixed number of virtqueues. Instead the maximum +number of virtqueues is chosen by the slave. The number can depend on host +resource availability or slave implementation details. Such devices are called +multiple queue devices. + Multiple queue support allows the slave to advertise the maximum number of queues. This is treated as a protocol extension, hence the slave has to implement protocol features first. The multiple queues feature is supported @@ -339,6 +348,14 @@ queue in the sent message to identify a specified queue. The master enables queues by sending message ``VHOST_USER_SET_VRING_ENABLE``. vhost-user-net has historically automatically enabled the first queue pair. +Slaves should always implement the ``VHOST_USER_PROTOCOL_F_MQ`` protocol +feature, even for devices with a fixed number of virtqueues, since it is simple +to implement and offers a degree of introspection. + +Masters must not rely on the ``VHOST_USER_PROTOCOL_F_MQ`` protocol feature for +devices with a fixed number of virtqueues. Only true multiqueue devices +require this protocol feature. + Migration --------- |