SDL2 output for pvh missing

[Stefan Kadow <xen@xxxxxxxx>]

Hello,

I am using xen 4.14.0 on arch linux, with SDL version 2.12.

When starting a domU of type "pvh" I do not get any SDL output. In the 
config file I set
type = "pvh"
vfb = ['vnc=0,sdl=1,keymap=de']

Is this something that should normally work?

The following things I already tried and checked:

1) I switched to vnc
vfb = ['vnc=1,vnclisten=0.0.0.0,sdl=0,keymap=de']

This works without problems! Within a VNC client I get a virtual 
terminal with login prompt and can start the xorg server.
2) I started a domU of type "pvhvm"
type = "hvm"
xen_platform_pci = 1
vga = "stdvga"
vnc = 0
sdl = 1

This works without problems! An SDL window opens, which I use for a 
complete KDE Plasma desktop.
3) An old Installation on the same Hardware, with xen 4.12.1 on arch 
linux and SDL version 1.2
This works without problems! An SDL window opens for domus of any kind, 
"pvh" and "pvhvm".
THX for any help!