On Fri, May 8, 2015 at 11:10 PM, Johnny Hughes <johnny@xxxxxxxxxx> wrote: > On 05/06/2015 09:27 AM, George Dunlap wrote: >> On Tue, May 5, 2015 at 2:07 PM, Johnny Hughes <johnny@xxxxxxxxxx> wrote: >>> WRT a new kernel .. the 3.18.x kernel has been selected to be maintained >>> as an LTS until Jan 2017. I think we should start work on rebuilding >>> this kernel and using it in the x4c projects. >>> >>> https://lwn.net/Articles/636289/ >>> >>> Thoughts? >>> >>> I will grab this kernel and try to roll in all the patches, etc. and see >>> if I can make it work. >> >> I did a little bit of work on building the 3.18 kernel a couple of >> weeks ago, but it looks like the blktap2.5 kernel code we were using >> before has totally bitrotted. >> >> I see three ways forward: >> >> 1. Try to do a "deep port" of the functionality, continuing to >> maintain it going forward. > > I did this with the kernel I released .. the blktap module is loaded > upon boot.. I did have to change some of the code based on this Debain bug: > > https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=748953 > > I have no idea how well this works .. we could use some testing of that > kernel here: > > http://people.centos.org/hughesjr/xen-kernel/ Right -- done by none other than Citrix's own Bob Ball... who updated it in his own github branch but then forgot to send a pull request to to the main XenServer repo, which is why I didn't see it. :-) >> 2. Start using the blktap3 code, which requires no kernel driver. >> >> 3. Drop blktap support, and ask people to use qdisk for vhd. >> >> Re #1, I'm not really excited about the idea of trying to keep porting >> those patches forward (and finding and fixing bugs in the forward-port >> each time). > > This has not been a huge problem in the past .. it mostly works OK. At > least no one has complained. The only time I had to change it was when > we moved from 3.6 to 3.10 and then from 3.10 to 3.18. But that does not > mean it works without issue, just that no one complained about it. Right... well I guess there are other users of the same code (which is why Bob submitted the fix last year), so we can hope that it's at least getting a little testing. If we give it a month of beta testing before releasing it, I think that's the best people can expect from a community-run project. >> In parallel to the Xen for C7 work I've been doing, I've been working >> on getting upstream Xen to build against XenServer's blktap code, with >> then aim of moving to blktap3. If we want to go with #2, then a major >> kernel update will have to wait until that work is done. > > I have no real preference .. just that we need a kernel update in 3 > months as in Sept 2015, 3.10 support stops at kernel.org. > > We can use the 3.18 LTS tree with my mods now, if it works for everyone > .. although the best way longterm seems to be to use blktap3 in the > future since that is what is in XenServer. Yes, using the forward-ported kernel blktap driver is probably the best thing to do until we have a replacement. -George _______________________________________________ CentOS-virt mailing list CentOS-virt@xxxxxxxxxx http://lists.centos.org/mailman/listinfo/centos-virt
