Bug 492866

Summary: Xen guest kernel advertises absolute mouse pointer feature which it is incapable of setting up correctly
Product: Red Hat Enterprise Linux 5 Reporter: Daniel Berrangé <berrange>
Component: kernel-xenAssignee: Markus Armbruster <armbru>
Status: CLOSED ERRATA QA Contact: Red Hat Kernel QE team <kernel-qe>
Severity: high Docs Contact:
Priority: high    
Version: 5.4CC: alanm, dzickus, emcnabb, mjenner, xen-maint
Target Milestone: rc   
Target Release: ---   
Hardware: All   
OS: Linux   
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of:
: 492868 (view as bug list) Environment:
Last Closed: 2009-09-02 08:17:04 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Bug Depends On:    
Bug Blocks: 223805, 492568    
Description Flags
Change PVFB not to select abs. pointer by default none

Description Daniel Berrangé 2009-03-30 13:28:59 UTC
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 18:14:14 UTC
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 18:17:31 UTC
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 16:00:33 UTC
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 12:17:20 UTC
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 08:17:04 UTC
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.