Re: Requesting for freeze exception for RMRR

From: Wei Liu <wei.liu2@citrix.com>
To: "Chen, Tiejun" <tiejun.chen@intel.com>
Cc: Kevin <kevin.tian@intel.com>, Wei Liu <wei.liu2@citrix.com>,
	"ian.campbell@citrix.com" <ian.campbell@citrix.com>,
	George Dunlap <George.Dunlap@eu.citrix.com>,
	Andrew Cooper <andrew.cooper3@citrix.com>,
	"ian.jackson@eu.citrix.com" <ian.jackson@eu.citrix.com>,
	"Wang, Yong Y" <yong.y.wang@intel.com>,
	"xen-devel@lists.xen.org" <xen-devel@lists.xen.org>,
	Jan Beulich <jbeulich@suse.com>
Subject: Re: Requesting for freeze exception for RMRR
Date: Fri, 17 Jul 2015 14:21:02 +0100	[thread overview]
Message-ID: <20150717132102.GL12455@zion.uk.xensource.com> (raw)
In-Reply-To: <20150717093041.GI12455@zion.uk.xensource.com>

On Fri, Jul 17, 2015 at 10:30:41AM +0100, Wei Liu wrote:
> On Fri, Jul 17, 2015 at 05:24:55PM +0800, Chen, Tiejun wrote:
> > >>* On hvmloader side, there three patches now:
> > >>   patch #5 is reviewed by George and Acked by Jan;
> > >>   patch #6 is reviewed just for code implementation but that solution can't
> > >>convince all maintainers. Honestly, this is a rare possibility of collision
> > >>in real world and the original pci allocation is not good so its hard to
> > >>reshape the original mechanism in one week. But actually we also have some
> > >>other solutions but we need a little time to figure out how to step forward
> > >>but I just think any solution wouldn't bring any change to other stuffs.
> > >>   patch #7 is pretty close to be Acked.
> > >>
> > >>So what's your final determination?
> > >>
> > >
> > >If you and maintainers can work out a solution for hvmloader bits today
> > >then yes, otherwise no.
> > >
> > 
> > Based on my understanding, we already have some solutions but we need some
> > time to put one into practice. I think its possible to work out this next
> > week. As you see other stuffs are almost closed so we can put our all effort
> > just on this bit.
> > 
> 
> Jan, Andrew and George, can you provide some insight? If that's the case
> we may be able to get that done within next week?
> 

I'm replying to myself because I read some emails from v7 to v9 and get
some basic ideas. Correct me if I'm wrong.

The major concern seems to be around the PCI allocation algorithm. Jan
has different opinion from George. George provided a simple solution
that will not make things worse than before, while Jan prefers to get
everything right.

To be fair, the PCI allocation code in a bad state is not really
contributor's fault.

Jan also pointed out on IRC he thinks the proper logic he asked for is
not very hard to implement.

Given we either take George's route, which already seems to have a
patch, or Jan's route, which he thinks shouldn't be too hard to
implement, I'm inclined to say give this series another week (24th
deadline still applied). Note that we've been working on this for ages,
any delay is going to burn up more energy than necessary.

Jan and George, if you disagree with what I say above, please reply.

Wei.

> Wei.
> 
> > Thanks
> > Tiejun