Behavior difference between xen and non-xen kernel

[Aaron Konstam]

The difference between the behavior of the xen and non-xen kernel in F7
on my laptop is puzzling. In grub.conf I have the lines:
title Fedora (2.6.20-2925.11.fc7xen)
        root (hd0,2)
        kernel /boot/xen.gz-2.6.20-2925.11.fc7
        module /boot/vmlinuz-2.6.20-2925.11.fc7xen ro root=LABEL=/ rhgb
quiet
        module /boot/initrd-2.6.20-2925.11.fc7xen.img
Booting this kernel indicates that cpu scaling is not supported and the
machine does not shut off when I do a shut down.

The lines for the non-xen kernel:
title Fedora (2.6.21-1.3228.fc7)
        root (hd0,2)
        kernel /boot/vmlinuz-2.6.21-1.3228.fc7 ro root=LABEL=/ rhgb
quiet
        initrd /boot/initrd-2.6.21-1.3228.fc7.img

when booted does support cpu scaling and dose shut off when I do a  shut
down.

Any explanations of this difference? Please don't laugh since I have
been telling people how to get their machines to shut off and I have
been  hosted on my own petard.

By the way what is the significance of the extra lines in the grub
clause for the xen kernel?
-- 
Aaron Konstam tel: (210) 656-0355 akonstam at sbcglobal.net