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Re: [Qemu-devel] [PATCH 3/4] s390/kvm: Add a channel I/O based virtio tr
From: |
Rusty Russell |
Subject: |
Re: [Qemu-devel] [PATCH 3/4] s390/kvm: Add a channel I/O based virtio transport driver. |
Date: |
Tue, 14 Aug 2012 09:40:01 +0930 |
User-agent: |
Notmuch/0.12 (http://notmuchmail.org) Emacs/23.3.1 (i686-pc-linux-gnu) |
On Mon, 13 Aug 2012 10:56:38 +0200, Cornelia Huck <address@hidden> wrote:
> On Wed, 08 Aug 2012 13:52:57 +0930
> Rusty Russell <address@hidden> wrote:
>
> > On Tue, 7 Aug 2012 16:52:47 +0200, Cornelia Huck <address@hidden> wrote:
> > 1) Please don't limit yourself to 32 feature bits! If you look at how
> > virtio_mmio does it, they use a selector to index into a
> > theoretically-infinite array of feature bits:
>
> It should be easy to extend the data processed by the feature ccws to a
> feature/index combination. Would it be practical to limit the index to
> an 8 bit value?
256 feature bits? That seems like it could one day be limiting. Or an
8 bit accessor into feature words? 8192 seems enough for anyone sane.
> > Note that we're also speculating a move to a new vring format, which
> > will probably be little-endian. But you probably want a completely new
> > ccw code for that anyway.
>
> Do you have a pointer to that discussion handy?
>
> If the host may support different vring formats, I'll probably want to
> add some kind of discovery mechanism for that as well (what discovery
> mechanism depends on whether this would be per-device or per-machine).
It would be per-machine; per-device would be a bit crazy. We'd
deprecate the old ring format.
There's been no consistent thread on the ideas for a ring change,
unfortunately, but you can find interesting parts here, off this thread:
Message-ID: <address@hidden>
Subject: Re: [RFC 7/11] virtio_pci: new, capability-aware driver.
Cheers,
Rusty.
- Re: [Qemu-devel] [PATCH 1/4] s390/kvm: Handle hosts not supporting s390-virtio., (continued)
Re: [Qemu-devel] [PATCH 1/4] s390/kvm: Handle hosts not supporting s390-virtio., Alexander Graf, 2012/08/09
[Qemu-devel] [PATCH 4/4] s390/kvm: Split out early console code., Cornelia Huck, 2012/08/07
[Qemu-devel] [PATCH 3/4] s390/kvm: Add a channel I/O based virtio transport driver., Cornelia Huck, 2012/08/07
Re: [Qemu-devel] [PATCH 3/4] s390/kvm: Add a channel I/O based virtio transport driver., Anthony Liguori, 2012/08/14
[Qemu-devel] [PATCH 2/4] s390: Add a mechanism to get the subchannel id., Cornelia Huck, 2012/08/07