virtio — archive

[PATCH v6 0/5] packed ring layout spec

From: Cornelia Huck <[email protected]>
To: [email protected]
Date: Wed, 10 Jan 2018 10:33:00 -0000

On Wed, 10 Jan 2018 11:47:53 +0200 "Michael S. Tsirkin" <[email protected]> wrote: > OK, this is in a shape where we could include it in the spec. > Changes from v5: > - scope reductions (see below). We can add more > features down the road, hopefully reduced scope will be enough > to finalize spec soon. > - cleanup and integrate in the spec > - pseudo-code > > Deferred features: > - dropped _F_DESC_LIST, 1.0 includes this unconditionally, we > can do same > - dropped event structure change notifications - needed for > efficient hardware implementations but let's add this on top > > 3 1st patches just move text around so all virtio 1.0 > things are in the same place. 2 last ones add the new layout > > Option to mark descriptors as not generating events isn't > yet implemented. Again, let's add this on top. > > I also note that for hardware implementations, a different > set of memory barriers is needed. Again, let's add this on top > > not linking into conformance sections, will add after spec > itself is approved. > > Michael S. Tsirkin (5): > content: move 1.0 queue format out to a separate section > content: move ring text out to a separate file > content: move virtqueue operation description > packed virtqueues: more efficient virtqueue layout > packed-ring: add in order request support > > conformance.tex | 4 +- > content.tex | 718 +++++ --------------------------------------------------- > packed-ring.tex | 692 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ > split-ring.tex | 666 ++++++++++++++++++++++++++++++++++++++++++++++++++++ > 4 files changed, 1423 insertions(+), 657 deletions(-) > create mode 100644 packed-ring.tex > create mode 100644 split-ring.tex > One thing I just noticed: This does not seem to contain any changes for transports. For ccw, we use different payloads in the SET_VQ command for legacy (pre-virtio-1) and virtio-1 split layout. I think we would need a new SET_VQ payload for the packed ring guarded by a new revision, but I have not investigated it yet. I have not yet thought through how this interacts with feature negotiation, either. Otherwise, I don't see any reason why the packed ring would not work fine for ccw as well.