Questions about compatibility between dom0 and domU kernels. In the ideal situation, all domU kernels would be patched to the same level of Xen in dom0. What happens if they are not? 1. Can an incompatible domU take down or in any way interfere with dom0? 2. Does Xen/dom0/Xend perform version checking on domUs? 3. Can a binary Xen kernel be queried for its compatibility version? 4. How frequently does the Xen compatibility interface change? 5. Can I run a 2.4 domU against a 2.6 dom0 and vice-versa, if both are patched to the same level of Xen? Thanks, Rich ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click _______________________________________________ Xen-devel mailing list Xen-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/xen-devel
> Questions about compatibility between dom0 and domU kernels. In the > ideal situation, all domU kernels would be patched to the > same level of > Xen in dom0. What happens if they are not? > > 1. Can an incompatible domU take down or in any way > interfere with dom0?No.> 2. Does Xen/dom0/Xend perform version checking on domUs?Yes.> 3. Can a binary Xen kernel be queried for its compatibility version?There''s a dom0 op that queries the interface version.> 4. How frequently does the Xen compatibility interface change?Only when there''s a major release number change.> 5. Can I run a 2.4 domU against a 2.6 dom0 and vice-versa, > if both are > patched to the same level of Xen?Yes. You can play with this on the Demo CD. Ian ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://ads.osdn.com/?ad_ide95&alloc_id396&op=click _______________________________________________ Xen-devel mailing list Xen-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/xen-devel
Ian Pratt wrote:>>2. Does Xen/dom0/Xend perform version checking on domUs? >> >> > >Yes. > >Out of curiosity, what happens in dom0 if a domU spoofs its interface version?>>3. Can a binary Xen kernel be queried for its compatibility version? >> >> > >There''s a dom0 op that queries the interface version. > >Is this accessible to the management tools, i.e. can Xend report the dom0 interface version to userland? If I have a domU binary kernel image (vmlinuz), is there any way to query its interface version (even a search string for strings+grep)?>>4. How frequently does the Xen compatibility interface change? >> >> > >Only when there''s a major release number change. > >Major = 1.x, 2.x, 3.x, not 2.0.4 to 2.0.5-pre, right? So the Xen interface is compatible between 2.0.4 and the testing/unstable tree. Rich ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click _______________________________________________ Xen-devel mailing list Xen-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/xen-devel
> Out of curiosity, what happens in dom0 if a domU spoofs its interface > version?The domU probably ends up crashing itself. It''s not a concern of dom0 or Xen anyhow,> >>3. Can a binary Xen kernel be queried for its > compatibility version? > >There''s a dom0 op that queries the interface version. > Is this accessible to the management tools, i.e. can Xend report the > dom0 interface version to userland?Yes.> If I have a domU binary kernel image (vmlinuz), is there any way to > query its interface version (even a search string for strings+grep)?As I recall, there''s a version identifier in the header.> >>4. How frequently does the Xen compatibility interface change?> >Only when there''s a major release number change. > > > > > Major = 1.x, 2.x, 3.x, not 2.0.4 to 2.0.5-pre, right? So the Xen > interface is compatible between 2.0.4 and the testing/unstable tree.2.0.x and 2.0-testing are compatible. Unstable is something entirely different, and is not guaranteed to be compatible with anything (other than the same version of itself). The original plan was to have 2.1.x compatible with 2.0.x, but I''m currently thinking that this will *not* be the case. Given current usage models, I don''t think that this is going to upset too many people. We''ll have to be much more careful to be backward compatible post 3.0. Ian ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://ads.osdn.com/?ad_ide95&alloc_id396&op=click _______________________________________________ Xen-devel mailing list Xen-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/xen-devel
On Mon, 07 Mar 2005 07:50:17 +0000, Ian Pratt <m+Ian.Pratt@cl.cam.ac.uk> wrote:>> Can I run a 2.4 domU against a 2.6 dom0 and vice-versa, >> if both are patched to the same level of Xen? > > Yes. You can play with this on the Demo CD.How does that work when dom0 is 100 Hz 2.4 kernel and domU is 1000 Hz 2.6 kernel? ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click _______________________________________________ Xen-devel mailing list Xen-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/xen-devel
Grzegorz Milos
2005-Mar-07 17:50 UTC
Re: [Xen-devel] Xen compatibility interface numbering
> >> Can I run a 2.4 domU against a 2.6 dom0 and vice-versa, > >> if both are patched to the same level of Xen? > > > > Yes. You can play with this on the Demo CD. > > How does that work when dom0 is 100 Hz 2.4 kernel and domU is 1000 Hz > 2.6 kernel?I will answer this question, although there might be better people to explain this. The scheduling code in both 2.4 and 2.6 kernels relay on hardware timer (to interrupt with 100 or 1000 Hz frequency). But the timers had to be virtualised, and therefore the parts of the code responsible for scheduling patched up as well. This way both linux kernels can work just fine. (BTW remember that Xen also has a scheduler which decides which domain should be run, but then the domains have freedom of scheduling their own processes). Cheers Gregor> > > > ------------------------------------------------------- > SF email is sponsored by - The IT Product Guide > Read honest & candid reviews on hundreds of IT Products from real users. > Discover which products truly live up to the hype. Start reading now. > http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/xen-devel-- Quidquid latine dictum sit, altum viditur --- Anon ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click _______________________________________________ Xen-devel mailing list Xen-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/xen-devel
Mark Williamson
2005-Mar-08 00:46 UTC
Re: [Xen-devel] Xen compatibility interface numbering
> How does that work when dom0 is 100 Hz 2.4 kernel and domU is 1000 Hz > 2.6 kernel?The dom0 kernel requests timer interrupts from Xen at 100HZ, the domU requests them at 1000HZ, Xen just delivers events when timers expire without caring what the domain does with them. In the situation you describe, the 2.4 kernel in dom0 would also be granted access to hardware devices. The 2.6 kernel would use virtual devices provided to it by dom0. The virtual device interfaces are independent of OS. HTH, Mark ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click _______________________________________________ Xen-devel mailing list Xen-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/xen-devel