OK - we are all Xen beginners here, so maybe if our discussions betray our ignorance, some patient folk might try to help us. I have had at least a start, but I had better explain the setup it has to work in.
I have 2 drives, one a SATA, partitioned up to sda10, all holding various distros. sda1 is a now unused small boot partition left over since its distro got trashed, and a different distro chose to make
grub point at its own spot in sda6. The other drive also contains a distro, but is unimportant to this discussion.
sda2 is swap, sda3 is the
extended partition holding all the others numbered 5 on upwards. There is no partition sda4. I just keep editing the
/boot/grub/menu.lst file in sda6, which is the place
grub first points to. There I add the pointers to any other distros. sda6 is known as (hd0,5) in grub-speak.
In my setup, sda6 is the " / " for the default distro (currently MEPIS 6.0). I checked the
Xen box on the Synaptic package manager, and the whole thing installed itself in one easy move, and Xen became one of the choices that come up with the bootsplash. Unfortunately, it failed to complete its script with a "file does not exist" or somesuch. There are several command line tools and internet how-tos, all different, and very opaque to me at this stage. I ended up commenting out the lines referring to Xen in menu.lst.
Much better things happened with the very recent
SUSE 10.2 I had installed SUSE / on sda9, with its /home partition on sda10, and I had checked the box for Xen during the install. I did not let it run grub again. Instead, I pinched the content of SUSE's /boot/grub/menu.lst, and copy-pasted it into my own version on sda6, and edited it to make (hd0,5)the path start point.
Wow! Its early days yet, but SUSE makes it really easy to have a play. On boot-up, there is the list of choices, with SUSE10.2, and Xen at the bottom of the list, timeout ticking away. So I selected "Xen", and the screen breaks into a flurry of passing script output messages, as if Xen is a little distro getting started. Then, apparently pre-set, it moves on to boot the SUSE 10.2 distro, (even though it was second last in the list!). Xen had taken 64M of RAM (or is it RAM + swap?). It looked and felt like a regular SUSE boot-up, but SUSE was running under Xen. I think this is what they call
domain0
The really interesing bit was to use the (spanner icon YAST system tool, and click the Xen icon) There you can "create" another virtual environment for other machines. This includes an option to simply do a fresh install of another system from a CD, or make "virtual drives" and can apparently boot other existing systems if you can point it to where the boot image is. I have not taken it further than this at this time.
One thing that might be important is that Xen is not a total emulator where the target system sees only the virtual hardware. Thats where it gets its speed. The target system must be co-operative to some extent. It must be configured to work with Xen. Yet Xen must be sufficiently in charge so as to be able to run even possibly hostile systems concurrently. So where I am right now is fooling with (admiring) the SUSE setup tools, but not yet actually made a second system run. I am not even sure it can be done without giving over all the space to SUSE/Xen, and re-installing in the created environments.
I don't say other configure routes are not also great, and I am still a bit p***d off with SUSE over video drivers and other things, but if you want to get real far, real quick with Xen, while possibly ducking the need to properly understand it, this is maybe the line of least resistance.
