[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Qemu-devel] Insane virtio-serial semantics

From: Anthony Liguori
Subject: Re: [Qemu-devel] Insane virtio-serial semantics
Date: Thu, 08 Dec 2011 08:37:38 -0600
User-agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv: Gecko/20110831 Lightning/1.0b2 Thunderbird/3.1.13

On 12/08/2011 04:11 AM, Markus Armbruster wrote:
Anthony Liguori<address@hidden>  writes:
And yes, I can't help but think of Dave Millers comments long ago that
any PV transport is eventually going to reinvent TCP, poorly.

No doubt then, no doubt now.  But if I remember correctly, we didn't
create virtio-serial because we thought we could do better than TCP/IP.
We thought we need a zero-config communication channel that doesn't
interfere in any way with the guest's networking.  Since the network
folks were unwilling to give us one ("use TCP already"), we looked for
another bare metal thing to imitate, and chose serial lines.

Now, comparing serial lines to TCP/IP makes no sense.  Different layers.

virtio-serial is not a serial line. It attempts to have connection semantics (like a socket) which is what the fundamental problem is.

It probably makes sense to have a virtio-serial2 that is exposed to the guest as a tty device and stick strictly to serial semantics.

Layering a real network protocol on top of serial line is possible; SLIP
exists.  But as long as we insist on "don't interfere in any way with
the guest's networking", we can't use TCP, and thus are doomed to
reinvent it, poorly.

I think we just got too clever.


Anthony Liguori

reply via email to

[Prev in Thread] Current Thread [Next in Thread]