HVM, USB Drives, .img files, VM recovery

[johny...@sigaint.org]

Is there any way to boot an HVM from an external USB drive?

I would have thought that simply setting the "additional drive" on a new
HVM to a USB device in another HVM (or dom0) would have allowed it to boot
from that drive.

I have a USB drive that contains a Linux system (partition table, /boot,
/) that I wouldn't mind booting under Qubes on occasion.

I tried creating an HVM and setting the additional drive to be that whole
drive, but upon startup it just complains that there is no bootable drive.

Hitting F12 for the boot menu doesn't let you be more specific than
CDROM/Hard disk, so you can't specifically choose which hard disk.

(Also, hitting F12 for the boot menu on time takes Ninja-like skills; is
there any way to make that easier?)

I can't see the utility of "additional drive" as an "hd" if you can't boot
from it. I feel like I'm missing something obvious.

I also tried removing the existing references to the root/volatile/private
.img files via qvm-prefs (hoping to encourage booting from the "additional
drive") but it wouldn't let me.

(I was going to make a suggestion that qemu-img be available in dom0 for
some unsupported recovery-style operations, but I see it is there under
/usr/lib/xen/bin. Good to know, for emergencies/recovery, and it does
make sense not to have it on the path or in an obvious spot, to avoid
encouraging unsupported and potentially dangerous actions. Good enough.)

Also, just FYI, I was able to recover some template/app VM's from
/lost+found in a toasted Qubes installation (due to that root USB issue I
was having) by simply creating similar VMs in a new Qubes installation,
and copying the .img files to the appropriate /var/lib/qubes/ directory.
I'm doing backups now to avoid such needs in the future. :)

Thanks.

JJ