From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wei Liu Subject: Re: 9p file system for xen Date: Mon, 16 Nov 2015 17:35:59 +0000 Message-ID: <20151116173559.GC25764@citrix.com> References: <56461C8A.4080401@jma3.com> <20151116151658.GA22829@citrix.com> <564A0608.8050904@jma3.com> <20151116165129.GA25764@citrix.com> <564A10E1.4070607@jma3.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <564A10E1.4070607@jma3.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Linda Cc: Julien Grall , Wei Liu , xen-devel@lists.xen.org List-Id: xen-devel@lists.xenproject.org On Mon, Nov 16, 2015 at 10:22:41AM -0700, Linda wrote: > > > On 11/16/2015 9:51 AM, Wei Liu wrote: > >On Mon, Nov 16, 2015 at 09:36:24AM -0700, Linda wrote: > >>Hi Wei, > >> > >>On 11/16/2015 8:16 AM, Wei Liu wrote: > >>>Hi Linda > >>> > >>>On Fri, Nov 13, 2015 at 10:23:22AM -0700, Linda wrote: > >>>>Hello, > >>>> I worked this summer as an intern under Julien Grall and Wei Liu. My > >>>>project was to develop a prototype/proof of concept xen front/back end for > >>>>the 9p file system. I mostly hacked the virtio 9p system. > >>>> This project was not complete, at the end of the summer. Julien said > >>>>that you all wanted to include this in the next release of xen in January, > >>>>and offered to take it over. I told Julien I wanted to continue working on > >>>>it, which I have been doing, very much in the background. > >>>> I came upon a bug in my code recently that made me aware that I am not > >>>>clear what the expectation for what I deliver should be: i.e., whether it's > >>>>still a prototype, or whether this should be production software. > >>>> Right now, I do not modify the toolstack (I never learned how), but > >>>>rather start and pause my guest, and then modify xenstore, manually. I can > >>>>fix my bug in the same manner, but this will limit the usefulness of what I > >>>>deliver. To do more will hit up against the limitations of my time and > >>>>knowledge. > >>>> So please let me know what you're expecting, especially wrt the user > >>>>interface, and when I would need to complete everything for this release. > >>>> > >>>If I interpret this correctly, you have a prototype that's working? Do > >>>you have your code somewhere? > >>No. I hit a bug that I would fix differently, depending on my goal. > >>>I think we would still like to include it in next release if possible -- > >>>that would require a properly implemented solution, not just a > >>>prototype. Let's assess the current situation and then decide what to > >>The situation is, given my current knowledge and what my availability has > >>been (it may improve), I can either: > >> a. Get a decent prototype working by the end of the year. This would > >>have certain values pre-written in xenstore, that I'm currently doing > >>manually. There are potentially some issues with mounting that I suspect > >>need to be different for xen than they are for virtio - so either way, I > >>need a clarification of how xen people want this to work. > >> b. Make sure what I've written is working, and pass it on to someone > >>else to update the toolstack, and resolve the issues, described above. In > >>this scenario, I would need to know how much time that someone would need > >>and just devote a week to getting this to them. > >> > >Your description is too vague. I don't have clear idea what kind of bug > >you encountered and what suggestion I can give. > The bug is a timing issue: During virtio's probe step, on the front end, it > initialized the mount path. Since at that time, the front end doesn't have > access to the back end's entries in xenstore (AFIACT), I either need to put > it in xenstore prior to starting, or move the access to this information to > later in the initialization. > > Note, I used the past tense on what virtio did, as of last summer: when I > looked at it last week, it appears to have changed since I first used it as > a template. I need to investigate this further. > OK. > Finally, I've made no provision for how to mount more than one file system > for the same guest. This is a feature that virtio provides for in the > front-end code (as do I), but I am unclear about how this works in the > back-end or at the user level. This is what I suspect will be different in > xen, and I'd like some input on what it should look like. I think this comes down to how your design the xenstore protocol to represent different mount points. > >The code freeze for next release is going to be end of March next year. > >As software engineer often overestimates the progress he or she can > >make, I would say we shall aim for getting something working as soon as > >possible. Get the design straight and something clean by the end of this > >year would be good. > Sounds good to me. I'm happy to keep working on this. I just didn't want > to find myself in a position where I needed to pass this on to someone else, > but I didn't give that person enough time to finish what I'd done. Depending on the situation, I can take over the code. You've done enough for this project and we don't really want you to work on it for free -- we don't have provision for more funding at the moment. If we end up taking over the project, we will still attribute the initial implementation to you. Wei.