Re: [Fedora-xen] Fedora 7 kernels

On Tue, Sep 25, 2007 at 04:17:24PM -0400, Jason Solan wrote: > I've had a lot of problems with Fedora 7 and XEN and I've read some > messages on this mailing list indicating the F7 kernel is more or less > broke with xen. > By problems I mean that 32 bit guests on 64 bit dom0 does not work at > all for me. Neither paravirtualized (as was a main feature of xen 3.1) > or fully virtualized. The release notes associated with Xen 3.1 turned out to be not quite accurate on the subject of 32-on-64 & we didn't realize this when we made corresponding release notes for Fedora 7. Xen 3.1 lets you run a 32-bit DomU kernel on a 64-bit hypervisor + Dom0 *ONLY IF* the DomU kernel was also based on Xen 3.1. ie, a 32-bit DomU kernel based on older Xen 3.0.* release would will not work on Xen 3.1 Unfortunately all the Fedora kernels for FC6 are 3.0.3 and F7 GA was based on Xen 3.0.4, so neither will work on a Xen 3.1 hypervisor + Dom0. In the current Xen-unstable upstream (which will become Xen 3.2) there is now back-compat support for running older DomU kernels. In the most recent update of Xen in F-7 updates-testing we have included a handful of backports which at least let us boot a 32-bit FC6 and F7 domU installer kernel on a 64-bit F7 / F8 host. There are ongoing fixes in upstream Xen for various stability issues when running 32-on-64 though, so it is not perfect. You may be lucky with our latest updates and have it work, but equally you may not be lucky. We're tracking upstream & will pull in fixes when available. > Combinations I've tried: > F7 x86_64 dom0 -> F7 x86 domU PV Works in basic testing. Has stability problems. > F7 x86_64 dom0 -> F7 x86 domU HVM F7 HVM has been broken since GA for reasons unrelated to the 32-on-64 stuff. A last minute clock-source & bootloader change screwed things up. Yesterday we pushed newer kernel-xen and xen RPMs to updates-testing which hopefully make this work. > RHEL 5 x86_64 dom0 -> F7 x86 domU HVM Not going to work - missing the fix I mention above. > RHEL 5.1 Beta x86_64 dom0 -> F7 x86 domU PV Works for me, at least to boot the installer. There are sometimes some stability issues though, since Xen 3.1 was far from complete in its 32-on-64 support. > RHEL 5.1 Beta x86_64 dom0 -> F7 x86 domU HVM Not going to work - missing the fix I mention above. > RHEL 5 x86 dom0 -> F7 x86 domU PV -- Only one that works (32 on 32 PV) Matched 32-on-32 and 64-on-64 kernels have always worked. > I had read a while ago (June?) that a kernel update would be coming soon > to fix the 32 on 64 PV issue, however I've ran in several new kernels > and none seem to fix the issue. > https://www.redhat.com/archives/fedora-xen/2007-June/msg00031.html The fix required both kernel-xen & xen updates which are finally available in updates-testing. > I've also repeatedly tried to run a 32 bit HVM fedora 7 guest on 64 bit > machines and had that fail similar to this: F7 HVM guests have known issues, also hopefully now fixed. > http://www.redhat.com/archives/fedora-xen/2007-June/msg00094.html > > Is there any more work planned for Fedora 7 and xen, or should I just > wait until F8? Or am I just doing something wrong and the problems I'm > having should be working on the current builds? Fedora 7 will continue to have updates until its end-of-life. The issue is that even in upstream Xen 32-on-64 doesn't have the same level of stability as 32-on-32, or 64-on-64. Dan.