Bug 493627 - The evdev keycodes are missing a definition for <LSGT>
The evdev keycodes are missing a definition for <LSGT>
Product: Red Hat Enterprise Linux 5
Classification: Red Hat
Component: xkeyboard-config (Show other bugs)
All Linux
low Severity medium
: rc
: ---
Assigned To: Peter Hutterer
: EasyFix, Patch
Depends On:
  Show dependency treegraph
Reported: 2009-04-02 08:55 EDT by john.haxby@oracle.com
Modified: 2009-07-31 10:44 EDT (History)
0 users

See Also:
Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of:
Last Closed: 2009-07-30 14:28:48 EDT
Type: ---
Regression: ---
Mount Type: ---
Documentation: ---
Verified Versions:
Category: ---
oVirt Team: ---
RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: ---

Attachments (Terms of Use)
Patch to add the missing definition (420 bytes, patch)
2009-04-02 08:55 EDT, john.haxby@oracle.com
no flags Details | Diff

External Trackers
Tracker ID Priority Status Summary Last Updated
FreeDesktop.org 7347 None None None Never

  None (edit)
Description john.haxby@oracle.com 2009-04-02 08:55:48 EDT
Created attachment 337800 [details]
Patch to add the missing definition

Description of problem:

If you configure a keyboard using the xkb-extended evdev driver (see bug 493623) then the definition for the "extra" key on a pc105 keyboard is missing.  This is the <LSGT> that sits between the "Z" and the left-shift key on the bottom row of the keyboard.

Version-Release number of selected component (if applicable): 0.8-7

How reproducible:

Steps to Reproduce:
1. Obtain a pc105 keyboard that can be used with the evdev driver
2. Configure the X server to use the evdev driver -- eg as for the Xen virtual keyboard pointer (see bug 493623)
3. Attempt to use the <LSGT> key, the one between the "Z" and the left shift key.
Actual results:  Nothing happens

Expected results: Depending on the keyboard layout you should see "<" ">" from this key or, for example, with a UK keyboard you get "\" and "|".

Additional info:  This same patch appears in later versions of Fedora.
Comment 1 john.haxby@oracle.com 2009-04-02 09:59:05 EDT
Related bugs: bug 493618, bug 493623, bug 493627, bug 493630, bug 493634 and bug 493642
Comment 3 Markus Armbruster 2009-07-30 14:28:48 EDT
The bug as reported is about the difficulties to manually configure X
in a certain way, to get proper pointer tracking.  It is certainly
valid.  However, the real problem users care about is that pointer
tracking works very poorly (mouse hits invisible wall).

Upstram, we solved the problem by fixing numerous issues in various
places to make it work out of the box, from Fedora 11 on.

The patches proposed by the reporter solve the problem by making
manual configuration work.  They are unrelated to the upstream

Like the upstream solution, they're fairly invasive: they touch the
kernel and several user space packages.  This is a significant risk.
Moreover, splitting the device is an ABI change.  The question is
whether there are benefits to justify that.

We already put much less invasive changes into 5.4 to improve pointer
tracking (bug 492866).  They fix the "mouse hits invisible wall"
problem.  They still require a pointer grab, which virt-viewer makes
relatively painless.

So, the benefit of the proposed patches over what we've got already is
to enable manual configuration so that the mouse grab can be avoided.
While that's certainly nice, it doesn't justify the risk, in my

If you disagree, please reopen the bug.

Some technical background:

There are 3 pieces in the stack: VNC client, QEMU VNC server and the
guest's X.  The old, misbehaving setup has VNC client sending absolute
coordinates, which the VNC server sends through xenkbd to X.  X in
RHEL-5 doesn't have any auto-configuration of input devices, so it
just opens /dev/input/mice, and thus the guest kernel converts from
absolute to relative.  Because the VNC client has no knowledge of this
conversion, you get into situation where you hit an invisible wall in
the client when it thinks it has got to the virtual desktop boundary.

Now, if you had absolute coordinates being passed and used all the way
to X then it would trivially work, but this requires X configuration.
Recent X's do that automatically.  RHEL-5's X simply isn't capable of
that.  The patches proposed by the reporter add manual configuration
steps across a wide range of RPMs.

The fix we did for RHEL-5.4 is to make xenkbd *not* use absolute
coordinates, so the VNC server now sends relative coordinates.  This
removes the broken absolute -> relative conversion in the guest
kernel.  On its own this isn't sufficient, because you then get broken
absolute to relative conversion in the VNC server instead.  So we also
added the VNC relative mouse extension to QEMU and GTK-VNC.  Now the
VNC client is in charge of doing the absolute -> relative conversion.
This is good, as this is the only point in the stack capable of doing
the conversion correctly, to avoid hitting an invisible wall.  The
only restriction is that you must grab the host mouse pointer and hide
it, so you only see the guest drawn pointer.
Comment 4 Markus Armbruster 2009-07-31 10:44:59 EDT
By the way, RHEL-6 pointer tracking will be fine out of the box using absolute coordinates, just like upstream.

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