Re: Upgrade from FreeBSD-12.2 to FreeBSD-13.1 with xen-4.14.0 is not straightforward.

On Thu, Jun 02, 2022 at 02:42:30AM -0700, Brian Buhrow wrote:
> 	hello.  In the process of updating one of my FreeBSD-xen servers from FreeBSD-12.2 to
> FreeBSD-13.1, I ran into what I think is a documentation omition.
> After I updated the operating system, but not the xen kernel or xen tools, I got the following
> error messages shown below.  Essentially, the xen kernel claimed it couldn't find the FreeBSD kernel.
> 
> 	After struggling for a long time to get the xen-4.15.0 tools built, I was able to boot the
> system and bring up some of the domu's, see my other recent message on this topic.  However, I
> don't see anywhere in the documentation or the wiki pages that xen-4.14.0 doesn't work with
> FreeBSD-13.1.  Nor do I see any warnings about this issue.  It occurred to me that I'd probably
> done this the hard way and the real problem was that when I updated FreeBSD, I failed to update
> the gptboot file in the boot partition, which was originally installed with FreeBSD-12.1.  When
> I updated the xen tools and kernel to 4.15.0, I also updated the gptboot file in the boot
> partition of the boot drive.  my question is, is this a known issue?  That is, FreeBSD-13 needs
> a new gptboot installed in order to boot xen at all?  If that's right, can we get this
> documented somewhere, so folks dont run into this as they update from FreeBSD-12 to FreeBSD-13?

So yes, as you discovered the hard way, FreeBSD 13 requires a matching
loader in order to work correctly with Xen.  This is due to:

https://cgit.freebsd.org/src/commit/sys/x86/xen/pv.c?id=b6d85a5f51e4147452b35d76478fb9e191b7734b

As a user, where d oyou think it would be helpful for you to find this
information, in the Xen handbook chapter maybe?

https://docs.freebsd.org/en/books/handbook/virtualization/#virtualization-host-xen

Thanks, Roger.