iris: subslice assertion failure on some hardware during initialization
- OS: PTXdist (embedded distribution)
- GPU: 00:02.0 VGA compatible controller [0300]: Intel Corporation Device [8086:3ea9] (rev 01)
- Kernel version: 5.10.x and 5.15
- Mesa version: main (a1dea665)
- Desktop manager and compositor: Weston
Describe the issue
Starting weston fails during gbm_create_device()
with:
intel_device_info.c:1656: intel_get_device_info_from_fd: Assertion `devinfo->subslice_total >= 1 || devinfo->ver <= 7' failed.
devinfo->subslice_total
is zero here.
Regression
This work with previous versions (e.g. 20.1.x). git bisect
found f08f8eaa as the commit that introduced the problem. Effectively reverting this commit fixes it.
It seems that I915_PARAM_SUBSLICE_TOTAL
returns the correct value. The new code derives the value from the data returned by DRM_I915_QUERY_TOPOLOGY_INFO
and this results in devinfo->subslice_total == 0
.
I don't know if Mesa or the kernel is wrong here. I've tested Linux v5.10.x and v5.15 and it happens with both versions.
So far I've only seen this with one hardware, an "Intel(R) Core(TM) i5-8260U CPU @ 1.60GHz". On any other hardware that I have available, both code versions calculate the same subslice_total
value.