Re: [tlug] xen and windows

[Simon Cozens <simon@example.com>]

Mike Mazur wrote:
> When I looked into Xen I discovered that you have to assign a certain
> portion of your RAM to your "host OS" (dom0 in Xen terminology[1]) at
> boot time, with the remainder left for your guest OSs when they start
> up. This means when I have no VMs running, a chunk of my RAM is
> inaccessible.

This is completely untrue, and completely confused.

You're using vmware concepts ("host OS", "guest OS") when discussing
Xen, which doesn't use those concepts. But even in doing so, you take an
argument that would be crazy in VMWare ("My host OS requires RAM to run!
How bad is that!") and apply it in Xen; it doesn't make any more sense
there either.

dom0 is not a host OS; dom0 is a privileged domain. You can't usefully
have "no VMs running" with Xen. If you completely ignore your dom0, then
yes, it's a waste of RAM. So don't do that.

dom0 is your first "guest OS". Xen is your "host OS". Now Xen itself
takes a bit of RAM to operate, I'll grant you, but that's an unfortunate
artifact of actually using any non-trivial software.

-- 
Timesharing just doesn't work. -K. Thompson, 1982.