Xen users - Jun 2009 - Unable to access parallel port from domU

I could use a little community help debugging a Xen device issue.

I am converting a Windows-based VMWare guest to become a Linux based Xen
guest.  Everything has gone well, except for the guest access to the host
parallel port.  (Yes, it''s old technology, but we have a parallel port
license dongle we have to support so we''re stuck.)  I''ve read
the few
threads I could find on this, but I''m still stuck.  Here are the
details,
and what I''ve done.

Host system: OpenSUSE 11.1, 2.6.27.23-0.1-xen kernel.  Latest maintenance
installed.
Processor (per /proc/cpuinfo): Dual-Core AMD Opteron Processor 1220
Processor flags: fpu de tsc msr pae cx8 apic mtrr cmov pat clflush mmx fxsr
sse sse2 ht syscall nx mmxext fxsr_opt lm 3dnowext 3dnow rep_good nopl
pnicx16 lahf_lm cmp_legacy extapic cr8_legacy
Xen: 3.3.1_18546_16-0.1.1
Guest OS: Windows 2000, all maintenance applied.  (I know, not formally
supported, but seems to be working well in general).
Host/guest parallel port IRQ: 7
Host parallel port IO range: 0378-037a (per /proc/ioports before I
blacklisted modules)
Guest parallel port IO range: 0378-037f (per device management tab)
Blacklisted host modules: lp, parport, parport_pc
Host permissions: /dev/lp0 = 0666.

Guest configuration:
  name="vsvr5"
  uuid="e0cee623-aa8b-3932-62ad-22396dedc639"
  memory=1536
  maxmem=1536
  vcpus=1
  on_poweroff="destroy"
  on_reboot="restart"
  on_crash="restart"
  localtime=1
  keymap="en-us"
  builder="hvm"
  extid=0
  device_model="/usr/lib/xen/bin/qemu-dm"
  kernel="/usr/lib/xen/boot/hvmloader"
  boot="cd"
  disk=[ ''phy:/dev/system/vsvr5-c-os,ioemu:hda,w'',
''phy:/dev/system/vsvr5-d-mssql,ioemu:hdc,w'',
''phy:/dev/system/vsvr5-f-sep,ioemu:hdd,w'']
  vif=[ ''mac=00:16:3e:4e:20:46,bridge=br0,model=rtl8139'', ]
  sdl=0
  ioports=[''0378-037F'']
  irq=[7]
  stdvga=0
  vnc=1
  vncconsole=0
  vncdisplay=5
  vncunused=1
  apic=1
  acpi=1
  pae=0
  usb=1
  usbdevice=''tablet''
  serial="pty"

Diagnostics taken:
- To remove any issues regarding the dongle or it''s associated software
in
the guest, I replaced the dongle with an HP Laserjet 4 printer.  I defined a
printer to the Win 2K guest on the parallel port.  When I print to it, the
guest believes the document printed (item goes into print queue, then queue
becomes empty without any errors reported), but nothing appears on the
printer.  I then shut down the guest, ran modprobe on the three blacklisted
modules on the host system, defined the printer to CUPS on the host system,
and printed to it successfully.  This indicates to me that the hardware is
good, as is the host system''s access to it.
- I''ve checked the host system Xen logs, xm dmesg, host dmesg, and host
messages log.

I am concerned that Linux and Win2K had slightly different IO address
ranges, but suspect this is a matter of "allocated" vs. "actually
used".

Any ideas as to how I can resolve this?  My migration is stalled until I can
get this resolved.

Thanks in advance...

                               -Brian





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