On 09/07/2017 03:17 PM, Kevin Stange wrote: > On 09/06/2017 05:21 PM, Kevin Stange wrote: >> On 09/06/2017 08:40 AM, Johnny Hughes wrote: >>> On 09/05/2017 02:26 PM, Kevin Stange wrote: >>>> On 09/04/2017 05:27 PM, Johnny Hughes wrote: >>>>> On 09/04/2017 03:59 PM, Kevin Stange wrote: >>>>>> On 09/02/2017 08:11 AM, Johnny Hughes wrote: >>>>>>> On 09/01/2017 02:41 PM, Kevin Stange wrote: >>>>>>>> On 08/31/2017 07:50 AM, PJ Welsh wrote: >>>>>>>>> A recently created and fully functional CentOS 7.3 VM fails to boot >>>>>>>>> after applying CR updates: >>>>>>>> <snip> >>>>>>>>> Server OS is CentOS 7.3 using Xen (no CR updates): >>>>>>>>> rpm -qa xen\* >>>>>>>>> xen-hypervisor-4.6.3-15.el7.x86_64 >>>>>>>>> xen-4.6.3-15.el7.x86_64 >>>>>>>>> xen-licenses-4.6.3-15.el7.x86_64 >>>>>>>>> xen-libs-4.6.3-15.el7.x86_64 >>>>>>>>> xen-runtime-4.6.3-15.el7.x86_64 >>>>>>>>> >>>>>>>>> uname -a >>>>>>>>> Linux tsxen2.xx.com <http://tsxen2.xx.com> 4.9.39-29.el7.x86_64 #1 SMP >>>>>>>>> Fri Jul 21 15:09:00 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux >>>>>>>>> >>>>>>>>> Sadly, the other issue is that the grub menu will not display for me to >>>>>>>>> select another kernel to see if it is just a kernel issue. >>>>>>>>> >>>>>>>>> The dracut prompt does not show any /dev/disk folder either. >>>>>>>>> >>>>>>>> >>>>>>>> I'm seeing this as well. My host is 4.9.44-29 and Xen 4.4.4-26 from >>>>>>>> testing repo, my guest is 3.10.0-693.1.1. Guest boots fine with >>>>>>>> 514.26.2. The kernel messages that appear to kick off the failure for >>>>>>>> me start with a page allocation failure. It eventually reaches dracut >>>>>>>> failures due to systemd/udev not setting up properly, but I think the >>>>>>>> root is this: >>>>>>>> >> <snip> >>>>>>> >>>>>>> Do any of you guys have access to RHEL to try the RHEL 7.4 Kernel? >>>>>> >>>>>> I think I may. I haven't tried yet, but I'll see if I can get my hands >>>>>> on one and test it tomorrow when I'm back at the office tomorrow. >>>>>> >>>>>> RH closed my bug as "WONTFIX" so far, saying Red Hat Quality Engineering >>>>>> Management declined the request. I started to look at the Red Hat >>>>>> source browser to see the list of patches from 693 to 514, but getting >>>>>> the full list seems impossible because the change log only goes back to >>>>>> 644 and there doesn't seem to be a way to obtain full builds of >>>>>> unreleased kernels. Unless I'm mistaken. >>>>>> >>>>>> I will also do some digging via RH support if I can. >>>>>> >>>>> I would think that RH would want AWS support for RHEL 7.4 and I thought >>>>> AWS was run on Xen // Note: I could be wrong about that. >>>>> >>>>> In any event, at the very least, we can make a kernel that boots PV for >>>>> 7.4 at some point. >>>> >>>> AWS does run on Xen, but the modifications they make to Xen are not >>>> known to me nor which version of Xen they use. They may also run the >>>> domains as HVM, which seems to mitigate the issue here. >>>> >>>> I just verified this kernel issue exists on a RHEL 7.3 system image >>>> under the same conditions, when it's updated to RHEL 7.4 and kernel >>>> 3.10.0-693.2.1.el7.x86_64. >>>> >>> >>> One other option is to run the DomU's as PVHVM: >>> https://wiki.xen.org/wiki/Xen_Linux_PV_on_HVM_drivers >>> >>> That should be much better performance than HVM and may be a workable >>> solution for people who don't want to modify their VM kernel. >>> >>> Here is more info on PVHVM: >>> https://wiki.xen.org/wiki/PV_on_HVM >>> >>> ================ >>> Also heard from someone to try this Config file change to the base >>> kernel and rebuild: >>> >>> CONFIG_RANDOMIZE_BASE=n >> >> This suggestion was mirrored in the RH bugzilla as well, it worked, but >> the same issue does not exist in newer kernels which have the option on. >> I've posted updated findings in the CentOS bug, which includes a patch >> that I found which seems to fix the issue: >> >> https://bugs.centos.org/view.php?id=13763#c30014 > > With many thanks to hughesjr and toracat, I was able to find a patch > that seems to resolve this issue and get it into CentOS Plus > 3.10.0-693.2.1. I've asked Red Hat to apply it to some future kernel > update, but that is only a dream for now. > > In the meantime, if anyone who has been experiencing the issue with PV > domains can try out the CentOS Plus kernel here and provide feedback, > I'd appreciate it! > > https://buildlogs.centos.org/c7-plus/kernel-plus/20170907163005/3.10.0-693.2.1.el7.centos.plus.x86_64/ > I can verify that PV-on-HVM mode works with the regular kernel as well if that is an option for you. Many public clouds (like AWS) require HVM or PV-on-HVM. See these for more information on PV-on-HVM: https://wiki.xen.org/wiki/PV_on_HVM https://wiki.xen.org/wiki/Xen_Linux_PV_on_HVM_drivers
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