Re: xen & uefi

[Robert Swindells <rjs%fdy2.co.uk@localhost>]

Patrick Welche <prlw1%cam.ac.uk@localhost> wrote:
>On Fri, Mar 20, 2020 at 10:11:13AM -0400, Brad Spencer wrote:
>> Patrick Welche <prlw1%cam.ac.uk@localhost> writes:
>> 
>> > Is booting into xen from uefi meant to work?
>> >
>> > I have a slightly unorthdox set up, but get:
>> >
>> >>> NetBSD/x86 EFI Boot (x64), Revision 1.1 (Tue Jan 28 13:49:42 UTC 2020) (from)
>> > ...
>> > Start @ 0xce600000 [1=0xce982000-0xce9820ec]...
>> > Trampoline space cannot be allocated; will try fallback.
>> 
>> I didn't think that a DOM0 + UEFI worked anywhere very well at this
>> point or at least was not a default...
>> 
>> See https://wiki.xenproject.org/wiki/Xen_EFI for example...
>> or ... https://ubuntuforums.org/showthread.php?t=2413434

>Thanks - that makes more sense. From boot(8)
>
>        multiboot kernel [arguments]
>               Boot the specified kernel, using the "multiboot" protocol
>               instead of the native NetBSD boot protocol...

The man page doesn't really describe the different things that could
happen.

The old 32-bit bootloader used the older multiboot protocol to talk to
a kernel.

There is multiboot2 support in efiboot, it will be running in 64-bit
mode when it calls into whatever kernel it has been told to load.

>Would that be different to the "multiboot2" mentioned in
>
>  https://patchwork.kernel.org/patch/9572493/

Yes, that is a patch to get Linux to work when loaded by a multiboot2
bootloader.

You care about what support is in Xen for this, which could also depend
on how pkgsrc builds the xen kernel.

Whichever bootloader is used it won't call into the DOM0, only the Xen
kernel.