[Libvirt] Failed to get udev device for syspath '/sys/devices/virtual/dmi/id'

[Mathieu Tarral <mathieu.tarral@xxxxxxxxxxxxxx>]

Hi,

I'm facing an issue with libvirt and the LIBXL driver, failing when searching 
for DMI data in /sys.

info : libvirt version: 5.0.0, package: 4+deb10u1 (Guido Günther 
<agx@xxxxxxxxxxx> Thu, 05 Dec 2019 00:22:14 +0100)
error : udevGetDMIData:1719 : internal error: Failed to get udev device for 
syspath '/sys/devices/virtual/dmi/id' or '/sys/class/dmi/id'
error : libxlDriverConfigNew:1803 : Unable to configure libxl's memory 
management parameters
error : virStateInitialize:662 : Initialization of LIBXL state driver failed: 
internal error: Failed to get udev device for syspath 
'/sys/devices/virtual/dmi/id' or '/sys/class/dmi/id'
error : daemonRunStateInit:799 : Driver state initialization failed

The relevant function udevGetDMIData in libvirt:
https://github.com/libvirt/libvirt/blob/cb09344a2cccc0cc9bcefa3cb53d7af45ba92631/src/node_device/node_device_udev.c#L1726

I don't understand what's happening, as this initialization failure only 
happens when I boot on the Xen kernel.
Also, the /sys/class/dmi* paths are not exposed on Xen. (should they ?)

Note: Running on Xen 4.12.1

Any ideas ?

Thanks !