Re: Xen 4.4 development update: RC0 imminent

From: Ian Campbell <Ian.Campbell@citrix.com>
To: Wei Liu <wei.liu2@citrix.com>
Cc: "George Dunlap" <george.dunlap@eu.citrix.com>,
	"Vladimir 'φ-coder/phcoder' Serbinenko" <phcoder@gmail.com>,
	"Fabio Fantoni" <fabio.fantoni@heliman.it>,
	"David Vrabel" <david.vrabel@citrix.com>,
	xen-devel <xen-devel@lists.xenproject.org>,
	"Roger Pau Monné" <roger.pau@citrix.com>
Subject: Re: Xen 4.4 development update: RC0 imminent
Date: Thu, 5 Dec 2013 17:16:55 +0000	[thread overview]
Message-ID: <1386263815.20047.137.camel@kazak.uk.xensource.com> (raw)
In-Reply-To: <20131205170652.GA29387@zion.uk.xensource.com>

On Thu, 2013-12-05 at 17:06 +0000, Wei Liu wrote:
> On Thu, Dec 05, 2013 at 04:59:20PM +0000, Ian Campbell wrote:
> > On Thu, 2013-12-05 at 16:48 +0000, Wei Liu wrote:
> > 
> > > > >>* Guest EFI booting (tianocore)
> > > > >>  - Wei Liu
> > > > >>
> > > > >A bunch of critical patches are neither applied upstream nor in our tree
> > > > >(though they are already acked / reviewed by maintainers), so I don't
> > > > >think we want to advertise it as "working"...
> > > > 
> > > > OK -- would the Xen side of these be something that could come in as
> > > > "bug fixes", or should I take this off the list of 4.4 features?
> > > >
> > > 
> > > I pinged maintainer this morning, let's see his response later. He's in
> > > GMT -8 timezone.
> > > 
> > > If we cannot get it merged within next week I would rather take it off
> > > our list.
> > 
> > IIRC the Xen side patches were pretty small and straight forward and the
> > only issue was agreeing the ABI for the struct passed from hvmloader to
> > ovmf.
> > 
> 
> Yes, that's the main missing bit. However the interface has been acked
> on OVMF side, does that mean it is safe to go in now?

I think so long as the risk that it might change is small we could take
it. The danger would be that we take it and release it and then someone
changes their mind or whatever. If they just spotted an issue then we'll
have to live with it -- just like we would if we committed to both ovmf
and Xen right now.

There's also an inherent danger in taking something into Xen without the
3rd party code which exercises it.

But the advantage is that when OVMF is updated it will be possible to
use it with Xen.

On the other hand if you need to build an OVMF yourself a few patches to
hvmloader are probably not a big deal either.

OK, so I'm clearly in two minds about this ;-)

George -- what do you think?

> > Other than that lack of ABI agreement is there anything else which would
> > block taking the patches on our side. In particular do they break what
> > little functionality there is with the existing ovmf code base which we
> > pull in?
> > 
> 
> No, it only makes OVMF work better than what we have now. ;-)
> 
> On the other hand I have two more patches for our build system. Shall I
> send them for review now?

It's probably a good idea to resend the whole lot anyhow.

Ian.