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From: Jamie Lokier <jamie@shareable.org>
To: Amit Shah <amit.shah@redhat.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>,
	virtualization@lists.linux-foundation.org,
	Gerd Hoffmann <kraxel@redhat.com>,
	kvm@vger.kernel.org, qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] Re: virtio-serial: An interface for host-guest communication
Date: Thu, 20 Aug 2009 18:10:18 +0100	[thread overview]
Message-ID: <20090820171018.GA2370@shareable.org> (raw)
In-Reply-To: <20090820075539.GA5876@amit-x200.redhat.com>

Amit Shah wrote:
> > I think strings are better as numbers for identifying protocols as you  
> > can work without a central registry for the numbers then.
> 
> I like the way assigned numbers work: it's simpler to code, needs a
> bitmap for all the ports that fits in nicely in the config space and
> udev rules / scripts can point /dev/vmch02 to /dev/console.

How would a third party go about assigning themselves a number?

For the sake of example, imagine they develop a simple service like
"guesttop" which let's the host get a listing of guest processes.

They'll have to distributed app-specific udev rule patches for every
guest distro, which sounds like a lot of work.  The app itself is
probably a very simple C program; the hardest part of making it
portable across distros would be the udev rules, which is silly.

Anyway, every other device has a name or uuid these days.  You can
still use /dev/sda1 to refer to your boot partition, but LABEL=boot is
also available if you prefer.  Isn't that the ethos these days?

Why not both?  /dev/vmch05 if you prefer, plus symlink
/dev/vmch-guesttop -> /dev/vmch05 if name=guesttop was given to QEMU.

If you do stay with numbers only, note that it's not like TCP/UDP port
numbers because the number space is far smaller.  Picking a random
number that you hope nobody else uses is harder.

... Back to technical bits.  If config space is tight, use a channel!
Dedicate channel 0 to control, used to fetch the name (if there is
one) for each number.

-- Jamie

  reply	other threads:[~2009-08-20 17:10 UTC|newest]

Thread overview: 62+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-07-27 18:04 [Qemu-devel] virtio-serial: An interface for host-guest communication Amit Shah
2009-07-27 18:04 ` [Qemu-devel] [PATCH 1/1] virtio_serial: A char device for simple guest <-> host communication Amit Shah
2009-07-27 18:04   ` [Qemu-devel] [PATCH 1/3] virtio-serial: virtio device for simple host <-> guest communication Amit Shah
2009-07-27 18:04     ` [Qemu-devel] [PATCH 2/3] vnc: add a is_vnc_active() helper Amit Shah
2009-07-27 18:04       ` [Qemu-devel] [PATCH 3/3] virtio-serial: vnc: support for sending / receiving guest clipboard Amit Shah
2009-08-05  0:03   ` [Qemu-devel] Re: [PATCH 1/1] virtio_serial: A char device for simple guest <-> host communication Rusty Russell
2009-08-05  5:12     ` Amit Shah
2009-08-05  9:58     ` Amit Shah
2009-07-27 20:22 ` [Qemu-devel] Re: virtio-serial: An interface for host-guest communication Anthony Liguori
2009-07-27 20:32   ` Daniel P. Berrange
2009-07-27 20:37     ` Anthony Liguori
2009-07-27 20:46     ` Jamie Lokier
2009-07-27 23:44       ` Anthony Liguori
2009-07-28 10:36         ` Amit Shah
     [not found]           ` <4A6F0048.1000103@codemonkey.ws>
2009-07-29  7:44             ` Amit Shah
2009-07-29  7:48               ` Gleb Natapov
2009-08-05 18:00                 ` Jamie Lokier
     [not found]         ` <20090728140029.GA16067@amd.home.annexia.org>
2009-07-28 14:48           ` Anthony Liguori
2009-07-28 14:55             ` Richard W.M. Jones
2009-07-28 15:00               ` Anthony Liguori
2009-08-03 19:57           ` Anthony Liguori
2009-08-05 17:57             ` Jamie Lokier
2009-08-05 18:00               ` Anthony Liguori
2009-08-06 10:38                 ` Amit Shah
2009-08-06 13:29                   ` Anthony Liguori
2009-08-06 13:41                     ` Amit Shah
2009-08-06 13:58                       ` Anthony Liguori
2009-08-06 14:04                         ` Amit Shah
2009-08-06 17:37                           ` Jamie Lokier
2009-08-07  6:38                             ` Amit Shah
2009-08-07 14:14                               ` Anthony Liguori
2009-08-10  6:55                                 ` Amit Shah
2009-08-10  9:47                                   ` Gerd Hoffmann
2009-08-10 13:02                                     ` Anthony Liguori
2009-08-10 14:02                                       ` Gerd Hoffmann
2009-08-10 14:20                                         ` Anthony Liguori
2009-08-10 15:34                                           ` Gerd Hoffmann
2009-08-10 16:59                                             ` Anthony Liguori
2009-08-10 17:27                                               ` Anthony Liguori
2009-08-12 18:27                                               ` Paul Brook
2009-08-14  8:15                                               ` Amit Shah
2009-08-14 13:29                                                 ` Anthony Liguori
2009-08-14 13:41                                                   ` Amit Shah
2009-08-20 13:42                                                   ` Amit Shah
2009-08-20 14:25                                                     ` Daniel P. Berrange
2009-08-20 14:38                                                       ` Amit Shah
2009-08-20 14:42                                                         ` Amit Shah
2009-08-14 13:49                                                 ` Gerd Hoffmann
2009-08-14 16:25                                                   ` Anthony Liguori
2009-08-20  7:31                                                     ` Rusty Russell
2009-08-20  7:44                                                       ` Gerd Hoffmann
2009-08-20  7:55                                                         ` Amit Shah
2009-08-20 17:10                                                           ` Jamie Lokier [this message]
2009-08-25 12:43                                                         ` Rusty Russell
2009-08-25 13:00                                                           ` Gerd Hoffmann
2009-08-10 14:20                                         ` Anthony Liguori
2009-08-10 23:09                                     ` Rusty Russell
2009-08-11  0:16                                       ` Anthony Liguori
2009-08-10 14:27                                   ` Anthony Liguori
2009-08-10 15:57                                     ` Gerd Hoffmann
2009-08-06 10:35               ` Amit Shah
2009-08-05 18:32             ` Richard W.M. Jones

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