Dear Maintainer,

This bug shows on my nvidia GT218 [GeForce210] graphics card using the nouveau
driver, on up-to-date Debian12.

The obvious effect of the bug is that xdvi runs REALLY slowly, taking ~4
seconds to display a page.  That makes xdvi pretty much unuseable.
As far as I can see xdvi (in fact xdvi-xaw which xdvi runs) uses XPutImage to
render text to the screen and XPutImage runs REALLY slowly.
  x11perf -putimage10 => 12000.0/sec # about 100 times slower than fixed version
  x11perf -putimagexy10 => 200.0/sec # about 500 times slower than fixed version

I accidentally found that disabling the "glamor" acceleration extension is an
effective workaround.  I disabled glamor by making a file
  /etc/X11/xorg.conf.d/10-noGlamor.conf
with contents
--------snip-------------
Section "Device"
        Identifier "nvidiaGraphicsCard"
        Driver "modesetting"
        Option "kmsdev" "/dev/dri/card0"
        Option "AccelMethod" "none" # "glamor"
EndSection
--------snip-------------

You can see from the log file that this successfully disables glamor.
After restarting X with glamor disabled, xdvi renders a page pretty much
instantly and
  x11perf -putimage10 => 1160000/sec
  x11perf -putimagexy10 => 103000/sec

I don't have access to any other machines with nvidia cards so I don't know
whether the bug would affect them also.  I hope this information & workaround
may help others.

Thanks for your attention

John Payne

Hello,

In the original bug report, I said
"This bug shows on my nvidia GT218 [GeForce210] graphics card using the nouveau
 driver, on up-to-date Debian12"
That is true, but rather misleading.
The bug also shows on my laptop (see Bug#1084062)
My laptop has an Intel IrisXe GPU and therefore does not use the nouveau driver.

I don't properly understand the X11 driver architecture but the common factors
between the two machines where the bug shows are the "modesetting driver" and
the "glamor" extension, so I suppose the bug is somewhere there.

Thanks for your attention

John Payne