Re: OVMF, lvm devices, and hvm guests

[T <bobs%thelibertytree.org@localhost>]

On Wed, 24 Aug 2022 15:17:59 -0400, Brad Spencer wrote:

> This is a set of notes and observations I acquired when looking into
> trying to use OVMF (uefi bios) with Xen HVM guests.  Sorry for the
> length.

> 1) If the kernel actually boots up, it will not be able to find it root
> filesystem and nothing that I put in telling it what that was helped.  I
> had actually noticed before that I was unable to use the new qemu-dm
> with old HVM guests and had to use use qemu traditional (and I think
> RomBIOS) instead.  Those HVM guests had the same problem in that the
> SeaBIOS could not find a bootable disk while the older qemu could.
> 
> 2) There was more than one DOM0 kernel panic / reboot that I didn't
> manage to catch even though I have ddb.onpanic set to 1.  This doesn't
> happen all of the time, but at least twice.  I don't know what the panic
> was, if there was one, as it happened too quickly and I wasn't present
> at the console.

> 
> In all cases, using a raw LVM LV produced these on the console (dozens
> and dozens of these lines):
> 
> Aug 24 13:37:23 dom0system /netbsd: [ 266.8875858] pmap_unwire: wiring
> for pmap 0xffffbf000535dba8 va 0x70343e1e7000 did not change!

Thought I'd stop back here and report what I've seen with a recent go at 
trying to get an HVM with ReactOS to work with NetBSD 9.3/Xen 4.15/LVM. I 
was seeing the same sort of issues described above: problems not finding 
the LVM devices, the crashes with pmap_unwire errors. I too switched the 
"device_model_version=qemu-xen-traditional" and the problems went away. I 
didn't try using a normal file in place of the LVM device, but I did have 
an ISO file mounted as a CD-ROM device and it was able to load, so that 
probably counts.