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Geoff 42

Member

Registered: 2016-12-15

Posts: 461  

Cursor redraws very slowly

I have an odd artifact involving the cursor redrawing very slowly
when it changes between cursors, say from the "I" cursor to the
"drag and stretch" cursor. It can take several seconds to complete
the redraw and seems to redraw by random scan lines. This also
similarly affects a certain type of pop-up.

My graphics card is an integrated Intel i915.

This artefact only occurs when I boot using the Xen hypervisor.
Booting on bare metal is ok, but booting with Xen produces this
slow redraw. I am currently on Devuan Chimaera, kernel 5.10.0-10-amd64
and Xen 4.14.4-pre although my failing memory tells me that I
had this effect earlier!

Devuan is booting in paravirtual mode (PV), as the controlling host
(Dom0). When I boot a guest system (DomU), the frame buffer of DomU
uses qemu, which runs in Dom0 and I can connect a vncviewer on
Dom0 to the qemu vncserver to access the X session on the DomU.
In this case the VNC display does not have this artefact.
If, however, I open an ssh connection to DomU and run a vncserver on DomU and
connect to it from Dom0 with a vncviewer, then the artefact
still occurs but to a lesser amount.

I wonder if anyone has encountered the slow redrawing of the
cursor and pop-ups. It would be really wonderful if anyone knows
how this ties in with Xen and even better if you know how to fix it!

Geoff