Re: running xen on current

[Brad Spencer <brad%anduin.eldar.org@localhost>]

Manuel Bouyer <bouyer%antioche.eu.org@localhost> writes:

> On Thu, Apr 15, 2021 at 09:53:50AM +0100, Patrick Welche wrote:
>> I have tried and failed to run xen on 3 -current/amd64 systems with
>> 3 different failure modes:
>> 
>> 1) laptop:  xen.gz Building a PV Dom0 / ELF: not an ELF binary -> panic/reboot
>> 2) desktop: XEN3_DOM0 panics including PR port-xen/55978
>> 3) server:  Trampoline space cannot be allocated; will try fallback -> reboot
>> 
>> They are all working NetBSD-current/amd64 systems.
>> 
>> My conclusion was that xen is hopelessly broken, so was quite surprised
>> by Greg Wood's thread about the finer points of running a guest OS, given
>> that those systems won't even start the host OS.
>> 
>> I dug out an old desktop, and to my pleasant surprise it booted XEN3_DOM0,
>> and I have managed to run some XEN3_DOMUs.
>> 
>> The difference between the working/broken setups seems to be that the
>> working one is "BIOS" booting rather than EFI booting.
>> 
>> Among all your xen success stories, are any of you EFI booting?
>
> AFAIK EFI is not yet supported by Xen (maybe this is supported by 4.15,
> I've not had a chance to try yet). I have it running on fairly recent
> Dell servers (in BIOS mode)


There has been fiddling with Xen and EFI for quite some time.  See:

https://wiki.xenproject.org/wiki/Xen_EFI

for example (might be old)... this indicates that Xen 4.3 or later could
be built as a EFI binary and probably booted from the EFI firmware
directly or with grub2 when grub2 is a EFI binary itself.  Of course
those instructions are all Linux-centric and I don't know if you created
a Xen kernel like this if it would boot a NetBSD DOM0 kernel.  I am in
no position to try any tests with this right now personally, but it is
tempting as I have a EFI only laptop that I could probably replace the
hard drive temporarily.



-- 
Brad Spencer - brad%anduin.eldar.org@localhost - KC8VKS - http://anduin.eldar.org