xsrc/58307: Slow/incremental updating of mouse cursor sprite

[Rhialto <rhialto%falu.nl@localhost>]

>Number:         58307
>Category:       xsrc
>Synopsis:       Slow/incremental updating of mouse cursor sprite
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    xsrc-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Jun 04 21:05:00 +0000 2024
>Originator:     Rhialto
>Release:        NetBSD 10.0
>Organization:
>Environment:
System: NetBSD murthe.falu.nl 10.0 NetBSD 10.0 (GENERIC) #0: Sat May 18 22:55:37 CEST 2024 rhialto%murthe.falu.nl@localhost:/mnt/scratch/scratch/tmp/xcrash/usr/src/sys/arch/amd64/compile/GENERIC amd64
Architecture: x86_64
Machine: amd64
>Description:
	When using Intel integrated graphics, and the modesetting driver
        for X, then when the mouse cursor changes shape, it isn't updated
        immediately. It happens incrementally over the course of sometimes
        several seconds. It is like the data is written into some kind
        of cache which isn't copied to its final destination
        immediately, but only as parts of it get pushed out because of
        evictions.

        I saw the same effect on different machines with different
        generations of Intel graphics (several years in between).

        Running xcompmgr has no effect on this. Probably because the
        mouse cursor is a sprite (or player missile graphics for the
        Atari fans).
>How-To-Repeat:
	in /etc/X11/xorg.conf, have
        Section "Device"
        ...
            Driver      "modesetting"
>Fix:
	I tried
	https://www.NetBSD.org/~riastradh/tmp/20240603/i915gemmmanpmapflags.patch	
	with the same change applied to the function below it as well.

	That seemed to fix the issue.
	I did not test yet if the patch in unchanged form is sufficient.