Subject: Re: [PATCH 12/28] virtio: console: Buffer data that comes in from the host

From: Rusty Russell <[email-masked]>
Date: Tue, 8 Dec 2009 11:46:10 +1030

On Fri, 4 Dec 2009 09:32:46 pm Amit Shah wrote:
> On (Thu) Dec 03 2009 [09:13:25], Amit Shah wrote:
> > On (Thu) Dec 03 2009 [09:24:23], Rusty Russell wrote:
> > > On Wed, 2 Dec 2009 07:54:06 pm Amit Shah wrote:
> > > > On (Wed) Dec 02 2009 [14:14:20], Rusty Russell wrote:
> > > > > On Sat, 28 Nov 2009 05:20:35 pm Amit Shah wrote:
> > > > > > The console could be flooded with data from the host; handle
> > > > > > this situation by buffering the data.
> > > > > 
> > > > > All this complexity makes me really wonder if we should just
> > > > > have the host say the max # ports it will ever use, and just do this
> > > > > really dumbly.  Yes, it's a limitation, but it'd be much simpler.
> > > > 
> > > > As in make sure the max nr ports is less than 255 and have per-port vqs?
> > > > And then the buffering will be done inside the vqs themselves?
> > > 
> > > Well < 128 (two vqs per port).  The config would say (with a feature bit)
> > > how many vq pairs there are.
> > 
> > Sure. This was how the previous versions behaved as well.
> 
> I forgot one detail:
> 
> http://www.mail-archive.com/[email-masked]/msg06079.html
> 
> Some API changes are needed to pre-declare the number of vqs and the
> selectively enable them as ports get added.

Couldn't we make it that all vqs *exist*, they're just unused unless the
bitmap (or whatever) indicates?

Thanks,
Rusty.