Bug 492866 - Xen guest kernel advertises absolute mouse pointer feature which it is incapable of setting up correctly
Xen guest kernel advertises absolute mouse pointer feature which it is incap...
Product: Red Hat Enterprise Linux 5
Classification: Red Hat
Component: kernel-xen (Show other bugs)
All Linux
high Severity high
: rc
: ---
Assigned To: Markus Armbruster
Red Hat Kernel QE team
Depends On:
Blocks: 223805 492568
  Show dependency treegraph
Reported: 2009-03-30 09:28 EDT by Daniel Berrange
Modified: 2009-09-02 04:17 EDT (History)
5 users (show)

See Also:
Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of:
: 492868 (view as bug list)
Last Closed: 2009-09-02 04:17:04 EDT
Type: ---
Regression: ---
Mount Type: ---
Documentation: ---
Verified Versions:
Category: ---
oVirt Team: ---
RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: ---

Attachments (Terms of Use)
Change PVFB not to select abs. pointer by default (1.40 KB, patch)
2009-04-14 14:17 EDT, Markus Armbruster
no flags Details | Diff

  None (edit)
Description Daniel Berrange 2009-03-30 09:28:59 EDT
Description of problem:
The PVFB graphics driver includes a paravirt mouse input device. When talking to the host OS over xenbus, it advertises that it supports absolute coordinate mode. RHEL-5 userspace is incapable of actually running the mouse in absolute mode by default though, so out of the box the guest OS is doing abs -> rel coordinate conversion.  This in turn causes problems for anyone connecting to the guest OS using the VNC server in the host OS because their mouse pointer will likely hit an invisible wall.

The absolute mouse coordinate feature should be disabled by default in RHEL-5 guest kernels. A boot parameter, or other tunable should be provided to allow absolute mode to be re-enabled  if the admin has manually configured an xorg.conf that supports it.

Version-Release number of selected component (if applicable):

How reproducible:

Steps to Reproduce:
1. Boot RHEL-5 guest
2. On host run xenstore-ls /local/domain/0/backend/vkbd
Actual results:
  feature-abs-pointer = "1"

Expected results:
  feature-abs-pointer = "0"

Additional info:
Comment 1 Markus Armbruster 2009-04-14 14:14:14 EDT
Xenstore node /local/domain/0/backend/vkbd shows whether the backend (host) offered the feature.  To see whether the frontend (guest) accepted it, which is what you want here, you run

# xenstore-read /local/domain/$DOMID/device/vkbd/0/request-abs-pointer
Comment 2 Markus Armbruster 2009-04-14 14:17:31 EDT
Created attachment 339538 [details]
Change PVFB not to select abs. pointer by default

This patch makes the xenkbd driver reject absolute pointers, unless they
are enabled with kernel parameter xenkbd.abs_pointer=1.
Comment 3 Don Zickus 2009-04-27 12:00:33 EDT
in kernel-2.6.18-141.el5
You can download this test kernel from http://people.redhat.com/dzickus/el5

Please do NOT transition this bugzilla state to VERIFIED until our QE team
has sent specific instructions indicating when to do so.  However feel free
to provide a comment indicating that this fix has been verified.
Comment 7 Alan Matsuoka 2009-06-05 08:17:20 EDT
The original change was at the request of the TAM. I've knocked it down to high/high since the fix is at the ON_QA state.
Comment 13 errata-xmlrpc 2009-09-02 04:17:04 EDT
An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on therefore solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.


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