Re: [PATCH] [Xend] Move some backend configuration

[John Levon <levon@movementarian.org>]

On Thu, Oct 02, 2008 at 03:04:48PM +0100, Keir Fraser wrote:

> > We're writing to the following paths that aren't standard:
> > 
> > device-misc/vif/default-link
> > hvmpv/{xpv,xdf,xpvd,xnf}/version
> > 
> > Can they be opened up? (Ideally we'd use the guest/ suggestion below,
> > and we will, but there's already stuff out there assuming it can do
> > this.)
> 
> What happens if you try to write them, and fail? What are they actually used
> for (e.g., communication with your own xvm tool stack?).

They're both tool stack values, so in the sense that we can permanently
patch xenstored, you don't need the change, you're right. Although, we're already
carrying way way too much customizations.

The former contains the "main" IP address of the domU. The latter
contain driver versions, to allow for the tool stack to determine a need
for updates. Note that neither are general enough to try and merge up as
a standard thing IMO, perhaps you disagree.

Regarding guest/ - xenstore is by far the simplest and easiest way to
communicate with the tool stack. I strongly doubt that we're the only
vendor to have done, or want to do, something like the above. Of course
there are caveats, but compared to the alternative (guest additions -
blech), it's pretty low cost.

I don't see it going away, so in my mind explicitly saying now that you
should only use guest/$(VENDOR) will avoid a lot of trouble down the
line.

regards
john