"nr_entries is too big" when using virgl

[Valentin David]

I have a bootable image where GNOME Shell fails because it hits a limit in virtio-gpu.

In `hw/display/virtio-gpu.c`, there is a limit for `nr_entries` at 16384. There is no explanation for that limit. But there does not seem to be any limit on the kernel side.

Raising this limit with a patch to 262144 solves the issue.

Could there be an explanation why this limit is needed? And why this value? Or could this limit be just removed?

[Gerd Hoffmann (kraxel-redhat)]

/me wonders what gnome shell is doing there ...

It is the number of scatter list entries for resources. Even in the worst case (no chunks are continous in memory so each single page needs an entry) this is enough for 64 MB. An 4k display
framebuffer needs less than that.

Removing the limit isn't an option. Raising maybe.

[Thomas Huth (th-huth)]

The QEMU project is currently moving its bug tracking to another system.
For this we need to know which bugs are still valid and which could be
closed already. Thus we are setting older bugs to "Incomplete" now.

If you still think this bug report here is valid, then please switch
the state back to "New" within the next 60 days, otherwise this report
will be marked as "Expired". Or please mark it as "Fix Released" if
the problem has been solved with a newer version of QEMU already.

Thank you and sorry for the inconvenience.

[Launchpad Janitor (janitor)]

[Expired for QEMU because there has been no activity for 60 days.]