Xen pvfb absolute/relative mystery, some findings

["Pasi Kärkkäinen" <pasik@iki.fi>]

Hello,

I just noticed something about the absolute/relative mouse 
that might be good to know.

My test-setup:

	Xen dom0:
		- Fedora 13 x86_64
		- Xen 4.0.1 rpms
		- Latest pvops dom0 kernel from xen.git xen/stable-2.6.32.x branch (2.6.32.21)
		- runlevel 3, no Xserver running.
		- vncviewer (tigervnc) default version from F13
		- virt-manager and virt-viewer default versions from F13

	Client 1:
		- Fedora 13 x86_64
		- Gnome desktop
		- Normal openssh from gnome-terminal

	Client 2:
		- Windows 7
		- Putty
		- Xming Xserver

General:
	- I run Xen PV guests on the Fedora 13 Xen dom0 host.
	- I use ssh X11 forwarding from the clients to connect to the dom0.
	- I run "virt-manager", "virt-viewer" and "vncviewer" on dom0, 
	  but display the GUI through ssh X11 forwarding on the clients.

And then the findings: If I get absolute or relative mouse depends 
what Xserver I use! In addition to what vnc program I use..

Test results:

	ssh from client 1 (F13) to dom0:
		- CentOS 5.5 guest, virt-manager,virt-viewer:	absolute, single cursor.
		- CentOS 5.5 guest, vncviewer:			relative, dual cursors.

		- Fedora 13 guest, virt-manager,virt-viewer:	absolute, single cursor.
		- Fedora 13 guest, vncviewer:			relative, dual cursors.

	ssh from client 2 (Win7+Xming) to dom0:
		- CentOS 5.5 guest, virt-manager,virt-viewer:	relative, dual cursors.
		- CentOS 5.5 guest, vncviewer:			relative, dual cursors.

		- Fedora 13 guest, virt-manager,virt-viewer:	relative, dual cursors.
		- Fedora 13 guest, vncviewer:			relative, dual cursors.		


I verified those multiple times, and they're reproducible every time.

Note that "virt-manager", "virt-viewer" and "vncviewer" versions 
are exactly the same for both clients, since I'm running them 
on dom0 and not on the clients! Clients only have Xserver to display the GUIs.

Reasons (my guess):
	- tigervnc vncviewer doesn't support some extension to get the absolute mode.
	- Xming Xserver on Windows doesn't support hiding the mouse cursor so we always get relative?

Also one interesting bug:
	- I tested the F13 guest from client 1 first.. all ok. Then I disconnected the console,
	  and then connected from client 2 (Xming). Now the mouse cursor got 'stuck'
	  on upper left corner of the screen.. It wouldn't move out from there anymore.
	  It was just kind of 'shaking' a bit around where it was.


-- Pasi