Can't start VMs after updating to Debian 12 bookworm from 11 bullseye (Xen 4.14 to 4.17)

[Scott Garron <xen-users@xxxxxxxxxxxxxxxxxx>]

After performing a dist-upgrade from Debian 11 (bullseye) to Debian 12 
(bookworm), and updating to Xen 4.17 from 4.14, I'm unable to start (xl 
create) any of my existing Xen domUs (consisting of pv and hvm guests).
I also attempted to create a new pv domU by following the Xen Project 
Beginners Guide tutorial on wiki.xenproject.org ( 
https://wiki.xenproject.org/wiki/Xen_Project_Beginners_Guide#Configuring_xen-tools_and_building_our_guest 
)  That yielded the same result.
The result of the xl create command is as follows:

simba@cyclone:/etc/xen$ sudo xl create tutorial-pv-guest.cfg
Parsing config from tutorial-pv-guest.cfg
libxl: error: libxl_create.c:1976:console_xswait_callback: domain 9 
console tty: timed out
libxl: error: libxl_domain.c:1183:libxl__destroy_domid: Domain 
9:Non-existant domain
libxl: error: libxl_domain.c:1137:domain_destroy_callback: Domain 
9:Unable to destroy guest
libxl: error: libxl_domain.c:1064:domain_destroy_cb: Domain 
9:Destruction of domain failed

tutorial-pv-guest.cfg has the following contents:

bootloader = 'pygrub'
vcpus       = '2'
memory      = '4096'
root        = '/dev/xvda2 ro'
disk        = [
                  'phy:/dev/cyclonevg2/tutorial-pv-guest-disk,xvda2,w',
                  'phy:/dev/cyclonevg2/tutorial-pv-guest-swap,xvda1,w',
              ]
name        = 'tutorial-pv-guest'
dhcp        = 'dhcp'
vif         = [ 'mac=00:16:3E:57:56:64, bridge=egint' ]
on_poweroff = 'destroy'
on_reboot   = 'restart'
on_crash    = 'restart'


/var/log/xen/bootloader.{id}.log shows a pyGrub selection screen, so it 
seems that the VM is at least getting somewhere, but xl create is timing 
out waiting for a console or something, and destroying the domU.
None of the other logs (syslog , kern.log) seem to show anything out of 
the ordinary.
Am I missing something obvious?


--
Scott Garron