I have a bit of a Xen theory question. I have a Debian 5 Lenny x64 Dom0 currently running two DomUs. One is an x64 built via Xen-tools, and it seems to be running great. The second (known as Alpha) is having some troubles, as I mentioned in my post "Ubuntu 8.04 DomU crash" to this list on 5/12/09. It is an x86/32 Ubuntu 8.04 that started life as an HVM and was rebuilt into a PV where it is today. It runs well for a day or two, then dies. Right now I''m just rebooting it while I decide what the best fix is. I knowit needs a different/newer kernel than what it''s running now. Here''s my real question: how much match-up must there be between the kernel of the Dom0 and of the PV DomU? Here, I have a Debian 5 x64 (2.6.26-2-xen-amd64) Dom0 and Ubuntu 8.04 x86-32 (2.6.24-23-xen) DomU. It seems to be known that that 2.6.24-23-xen is the problem, and 2.6.28.8 is recommended. Before I go recompile my DomU, I''m curious how closely they have to match? Like, if I have a newer Xen version in the DomU or the Dom0, do they get along ok? I also have little experience with x64 Linux -- I presume I can''t just boot my Ubuntu 8.04 (x86-32) DomU using the 2.6.26-2-xen-amd64 kernel my Dom0 uses, because that DomU is an entirely 32-bit Ubuntu, and the Dom0 is a 64-bit Debian kernel, right? Thanks in advance for suggestions. -- Chris ''Xenon'' Hanson, omo sanza lettere Xenon AlphaPixel.com PixelSense Landsat processing now available! http://www.alphapixel.com/demos/ "There is no Truth. There is only Perception. To Perceive is to Exist." - Xen _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On Wed, May 27, 2009 at 12:47 AM, Chris ''Xenon'' Hanson <xenon@alphapixel.com> wrote:> Here''s my real question: how much match-up must there be between the kernel of the Dom0 > and of the PV DomU?Newer kernels and hypervisors should be able to work even when their version are not exact match, provided that: - they are new enough (Xen >= 3.1 should be enough) - they are architecturally compatible (64bit hypervisor can work with 64bit and 32bit PAE kernel, but 32bit hypervisor can only work with 32bit kernel)> Here, I have a Debian 5 x64 (2.6.26-2-xen-amd64) Dom0 and Ubuntu 8.04 > x86-32 (2.6.24-23-xen) DomU. It seems to be known that that 2.6.24-23-xen is the problem, > and 2.6.28.8 is recommended.Really? by 2.6.28.8 I assume you mean pv_ops kernel. It works, but not all features of -xen kernel is available on pv_ops kernel yet. See http://wiki.xensource.com/xenwiki/XenParavirtOps Have you tried the suggestions on the previous thread? from my experience Debian''s kernel (or RHEL''s kernel, if you''re feeling adventurous) works quite nicely as domU kernel for Ubuntu. Plus you don''t have to compile anything.> > Before I go recompile my DomU, I''m curious how closely they have to match? Like, if I > have a newer Xen version in the DomU or the Dom0, do they get along ok?They should work OK. Some of the combinations I have on my setup : - Xen 3.3.1 and Xen 3.3.4 hypervisor, kernel from RHEL (xen 3.1.2+) as both dom0 and domU, Debian kernel as domU. - Opensolaris (Xen 3.1.4) hypervisor and dom0, RHEL (xen 3.1.2+) and Debian (xen 3.2.1?) kernel as domU. All of them are 64bit.> > I also have little experience with x64 Linux -- I presume I can''t just boot my Ubuntu > 8.04 (x86-32) DomU using the 2.6.26-2-xen-amd64 kernel my Dom0 uses, because that DomU is > an entirely 32-bit Ubuntu, and the Dom0 is a 64-bit Debian kernel, right?It should work, but you might have some problems with kernel module-userland interaction (e.g. using iptables). Try http://packages.debian.org/lenny/linux-image-2.6.26-2-xen-686 -- Fajar _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Chris ''Xenon'' Hanson
2009-May-27 04:12 UTC
Re: [Xen-users] Match between Dom0 and DomU PV
Fajar A. Nugraha wrote:> Newer kernels and hypervisors should be able to work even when their > version are not exact match, provided that: > - they are new enough (Xen >= 3.1 should be enough) > - they are architecturally compatible (64bit hypervisor can work with > 64bit and 32bit PAE kernel, but 32bit hypervisor can only work with > 32bit kernel)Ok. That''s what I assumed.>> Here, I have a Debian 5 x64 (2.6.26-2-xen-amd64) Dom0 and Ubuntu 8.04 >> x86-32 (2.6.24-23-xen) DomU. It seems to be known that that 2.6.24-23-xen is the problem, >> and 2.6.28.8 is recommended. > Really? by 2.6.28.8 I assume you mean pv_ops kernel. It works, but not > all features of -xen kernel is available on pv_ops kernel yet. See > http://wiki.xensource.com/xenwiki/XenParavirtOpsWell, I was basing that on the reply from Markus Schonhaber on 5/12: "I have neither found the root of the problem nor a solution. But replacing the domU''s Ubuntu kernel by a self-compiled recent vanilla kernel (2.6.28.8) with domU support is a workaround that lets the domU run stable since 54 days now - previously one week was the most I could get for uptime."> Have you tried the suggestions on the previous thread? from my > experience Debian''s kernel (or RHEL''s kernel, if you''re feeling > adventurous) works quite nicely as domU kernel for Ubuntu. Plus you > don''t have to compile anything.I wasn''t quite sure how to safely fetch Debian 5''s x86-32 kernel (and any supporting files needed) from my x64 Debian box without messing things up. I''d be _thrilled_ to sort things out without having to recompile a kernel, as this machine intentionally doens''t have dev tools installed on it (in Dom0 or DomU).>> I also have little experience with x64 Linux -- I presume I can''t just boot my Ubuntu >> 8.04 (x86-32) DomU using the 2.6.26-2-xen-amd64 kernel my Dom0 uses, because that DomU is >> an entirely 32-bit Ubuntu, and the Dom0 is a 64-bit Debian kernel, right? > It should work, but you might have some problems with kernel > module-userland interaction (e.g. using iptables). > Try http://packages.debian.org/lenny/linux-image-2.6.26-2-xen-686I grabbed that, but just dropping it in in place of the existing kernel made the DomU boot very angry. The gist of it is: WARNING: Couldn''t open directory /lib/modules/2.6.26-2-xen-686: No such file or directory FATAL: Could not open /lib/modules/2.6.26-2-xen-686/modules.dep.temp for writing: No such file or directory Here''s the config with the old kernel commented out: #kernel = ''/etc/xen/kernels/alpha/vmlinuz-2.6.24-23-xen'' kernel = ''/etc/xen/kernels/alpha/vmlinuz-2.6.26-2-xen-686'' ramdisk = ''/etc/xen/kernels/alpha/initrd.img-2.6.24-23-xen'' So, I''m guessing I''d need a 26-2 initrd.img too. I''ll have to look and see what package I might be able to get that from. -- Chris ''Xenon'' Hanson, omo sanza lettere Xenon AlphaPixel.com PixelSense Landsat processing now available! http://www.alphapixel.com/demos/ "There is no Truth. There is only Perception. To Perceive is to Exist." - Xen _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On Wed, May 27, 2009 at 11:12 AM, Chris ''Xenon'' Hanson <xenon@alphapixel.com> wrote:> I wasn''t quite sure how to safely fetch Debian 5''s x86-32 kernelI''m not sure what you mean here. When using apt, you fecth the kernel from domU (or at least on chrooted-ed environment after mounting domU''s fs) without having to change anything inside dom0.>> Try http://packages.debian.org/lenny/linux-image-2.6.26-2-xen-686 > > I grabbed that, but just dropping it in in place of the existing kernel made the DomU > boot very angry. The gist of it is:That page also lists dependency (marked in red). In particular, you''ll need http://packages.debian.org/lenny/linux-modules-2.6.26-2-xen-686> > WARNING: Couldn''t open directory /lib/modules/2.6.26-2-xen-686: No such file or directory > FATAL: Could not open /lib/modules/2.6.26-2-xen-686/modules.dep.temp for writing: No such > file or directory > > Here''s the config with the old kernel commented out: > > #kernel = ''/etc/xen/kernels/alpha/vmlinuz-2.6.24-23-xen'' > kernel = ''/etc/xen/kernels/alpha/vmlinuz-2.6.26-2-xen-686'' > ramdisk = ''/etc/xen/kernels/alpha/initrd.img-2.6.24-23-xen''Now I see what your problem is. You''re booting with kernels from dom0 aren''t you? It''s much easier to use pygrub. That way you could : - boot your domU with your current kernel - install the two packages manually, or follow Thiago''s post on http://lists.xensource.com/archives/html/xen-users/2009-05/msg00454.html (you might want to adjust which debian mirror you use). Again, this is done on domU, NOT on dom0. If you still want to put the kernel and initrd on dom0 anyway, copy it over from domU to dom0. -- Fajar _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users