Release notes addition for Xen support in Debian
Hi,
I intend to have the attached document added to the Squeeze release
notes. Also, what's the way to have it included? Should I send it as a
wishlist bug to the "release-notes" package, or something like that?
Could others please give me comments on this? Also, some correction for
my (poor) English would be welcome when/if you spot issues.
Thomas Goirand (zigo)
4.7.4. Upgrading with Xen installed, and Kernel enumeration order issue with Xen
In Lenny, using grub legacy, the following kernel order was respected:
- Xen hypervisor with Xen dom0 kernel
- Normal (eg: without dom0 support) kernel
- Xen dom0 kernel (without they hypervisor)
This order was the natural expected one, because if you installed Xen, it will simply boot the hypervisor and it's dom0 by default as expected.
Unfortunately, in Squeeze, when running with Grub2, this isn't what is happening. By default, the order is the exact opposite:
- Xen dom0 kernel (without they hypervisor)
- Normal (eg: without dom0 support) kernel
- Xen hypervisor with Xen dom0 kernel
As a consequence, if you have Xen installed and expect to boot with it by default, you have to tweak grub2 configuration. One of the way to hack before the grub maintainers can fix it the proper way could be to simply do:
ln -s 20_linux_xen /etc/grub.d/09_linux_xen_first
dpkg-reconfigure grub-pc
so that Xen is loaded first, by default, when using Grub2.
Another thing that you have to take care about when upgrading from Lenny, is that currently, Xen isn't upgraded to the 4.0 version that you should be expecting in Squeeze. So, after you finished the dist-upgrade, it is advised to check that Xen 4.0 and the corresponding dom0 kernel are installed. Under the 64 bits architecture, the following command will fix this:
apt-get install xen-utils-common xen-utils-4.0 xenstore-utils libxenstore3.0 xen-hypervisor-4.0-amd64 linux-image-2.6.32-5-xen-amd64
Here is the corresponding for 32 bits:
apt-get install xen-utils-common xen-utils-4.0 xenstore-utils libxenstore3.0 xen-hypervisor-4.0-i686 linux-image-2.6.32-5-xen-i686
Also, if you require HVM support, you will need to install the Xen Qemu device model, which is now a separate package:
apt-get install xen-qemu-dm-4.0
It is also important to notice that your domU wont be able to use sda1 (for example) as device name for their HDD. This naming scheme has been removed from Xen because of a request from the mainline kernel maintainers. Instead, you should use xvda1 (as a corresponding example) instead.
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