> Don't know if this is a known problem, but I didn't find anything about it
> with a quick google. I'm using Xen 3.1.0.
> I have found that if I try to create a large virtual device and boot from
> it within an HVM domU, I can't get it to work. The size I was trying to
> use was 250GB, with most of the space (about 240GB) allocated to a bootable
> WindowsXP NTFS partition. The failure mode was for the domU to crash and
> die with no messages other than a few lines of BIOS hardware discovery.
> I happend to notice that within the DomU SDL window, just before it dies,
> the BIOS reports the disk size as -6G (MINUS 6 Gig) rather than the
> expected 250G. This message comes from the BIOS of the LVM partition,
> just before it says it's trying to boot the OS. This sounds like a problem
> with signed/unsigned interpretation of the value 250GB. So, on a hunch, I
> used gparted to resize the NTFS filesystem, and the entire disk image, to
> smaller than 128GB. I chose 72GB. After lvresizing /dev/main/d4600_disk,
> I was able to successfully boot windows.
Sounds like your intuition was right.
> Now, I know that HVM virtual disks of comparable size _do_ normally work, I
> use them all the time.
Is that for non bootable for drives on HVM machines? That's a bigger drive
than I've ever tried myself :-)
> I suspect that what is going wrong is that the BIOS
> used by the DomU for initial boot has some bug or limitation that prevents
> it from booting from larger disk sizes.
Yes, that sounds reasonable.
> Does anybody know of such a limitation or bug in the BIOS? Or has anybody
> else been able to boot an HVM from a virtual disk of around 250GB, with the
> bootable partition taking up most of the disk?
I should think that it's a BIOS limitation. I'm cross posting this onto
xen-devel. Lets continue discussions just on that list, since I'm confident
from what you've said this is a limitation of the current BIOS code.
I've not heard of any changes to increase the supported sizes for a bootable
volume, but maybe I've just not seen it mentioned. Presumably you can work
around this by using a smaller boot disk? But I realise that's not really
Dave: Just a question. What use is a unicyle with no seat? And no pedals!
Mark: To answer a question with a question: What use is a skateboard?
Dave: Skateboards have wheels.
Mark: My wheel has a wheel!
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