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Re: [Qemu-devel] [PATCH 0/8] virtio-console: Move to qdev, multiple devi
From: |
Jamie Lokier |
Subject: |
Re: [Qemu-devel] [PATCH 0/8] virtio-console: Move to qdev, multiple devices, generic ports |
Date: |
Tue, 19 Jan 2010 17:59:33 +0000 |
User-agent: |
Mutt/1.5.13 (2006-08-11) |
Anthony Liguori wrote:
> I think this is a pretty fundamental issue to work out since it
> determines the very nature of the transport (stream vs. datagram).
For the record, I don't think there's anything _wrong_ with a datagram
transport. It would be quite useful sometimes. But if there is
datagram support, it should be optional, just like you can choose
between SOCK_STREAM and SOCK_DGRAM for AF_UNIX sockets.
Something else occurred to me with the cut buffer application:
What happens if the guest crashes, kexecs or whatever when it's half
way through sending a cut buffer? A stream protocol will not have a
nice way to recover from that unless there is an additional "out of
band" way to say "I'm starting again". Does virtio-serial have an
"I'm starting again" which is passed to the host side application?
> Because you have to put a max buffer size on the transport, I think
> buffering is a really flawed approach provably equivalent to just
> increasing the message size within the transport. In general, the later
> is a better approach because then the guest is using it's memory vs.
> using host memory.
I agree, using guest memory for the buffer also means there doesn't
have to be an arbitrary limit on the buffer size, or a time limit. It
can just wait there until it's consumed or the guest decides to restart.
-- Jamie
- [Qemu-devel] [PATCH 2/8] virtio-console: qdev conversion, new virtio-serial-bus, (continued)
- [Qemu-devel] [PATCH 2/8] virtio-console: qdev conversion, new virtio-serial-bus, Amit Shah, 2010/01/14
- [Qemu-devel] [PATCH 3/8] virtio-serial-bus: Maintain guest and host port open/close state, Amit Shah, 2010/01/14
- [Qemu-devel] [PATCH 4/8] virtio-serial-bus: Add a port 'name' property for port discovery in guests, Amit Shah, 2010/01/14
- [Qemu-devel] [PATCH 5/8] virtio-serial-bus: Add support for buffering guest output, throttling guests, Amit Shah, 2010/01/14
- [Qemu-devel] [PATCH 6/8] virtio-serial-bus: Add ability to hot-unplug ports, Amit Shah, 2010/01/14
- [Qemu-devel] [PATCH 7/8] virtio-serial: Add a 'virtserialport' device for generic serial port support, Amit Shah, 2010/01/14
- [Qemu-devel] [PATCH 8/8] Move virtio-serial to Makefile.objs, Amit Shah, 2010/01/14
Re: [Qemu-devel] [PATCH 0/8] virtio-console: Move to qdev, multiple devices, generic ports, Anthony Liguori, 2010/01/14
Re: [Qemu-devel] [PATCH 0/8] virtio-console: Move to qdev, multiple devices, generic ports,
Jamie Lokier <=
Re: [Qemu-devel] [PATCH 0/8] virtio-console: Move to qdev, multiple devices, generic ports, Amit Shah, 2010/01/19
[Qemu-devel] [PATCH 0/8] virtio-console: Move to qdev, multiple devices, generic ports, Amit Shah, 2010/01/19
- [Qemu-devel] [PATCH 1/8] virtio: Remove duplicate macro definition for max. virtqueues, bump up the max, Amit Shah, 2010/01/19
- [Qemu-devel] [PATCH 2/8] virtio-console: qdev conversion, new virtio-serial-bus, Amit Shah, 2010/01/19
- [Qemu-devel] [PATCH 3/8] virtio-serial-bus: Maintain guest and host port open/close state, Amit Shah, 2010/01/19
- [Qemu-devel] [PATCH 4/8] virtio-serial-bus: Add a port 'name' property for port discovery in guests, Amit Shah, 2010/01/19
- [Qemu-devel] [PATCH 5/8] virtio-serial-bus: Add ability to hot-unplug ports, Amit Shah, 2010/01/19
- [Qemu-devel] [PATCH 6/8] virtio-serial: Add a 'virtserialport' device for generic serial port support, Amit Shah, 2010/01/19
- [Qemu-devel] [PATCH 7/8] Move virtio-serial to Makefile.objs, Amit Shah, 2010/01/19
- [Qemu-devel] [PATCH 8/8] virtio-serial: Use MSI vectors for port virtqueues, Amit Shah, 2010/01/19