19 Aug
2009
19 Aug
'09
1:28 p.m.
On Wed, 19 Aug 2009 12:15:44 +0000, Andy Smith <andy(a)bitfolk.com> wrote:
Does that apply for domUs virtualised under HVM too? I thought a reboot on
an HVM domU went all the way back to the BIOS.
Tony
> Why is this? I thought that, at least on Ubuntu a
'shutdown -r' picks up
the latest
kernel?!
On a normal machine with grub, a reboot gets you to the point where
the BIOS runs grub and grub gets kernel, initrd, etc.
On a Xen domU with pygrub, on domain creation pygrub runs in dom0
(the host server) to read your filesystem, extract your grub config
file, parse it to find the kernel, initrd etc., extract *those* to
a temporary directory and then create a domU with those files.
But on a reboot, Xen never actually destroys the virtual machine, it
just starts it again. That means it will have the same kernel
(pygrub is never run), same amount of RAM, most probably the same
size disk devices as well (I have never tested that bit).