Public bug reported:
Following the recent update to Mesa 25.2.8 on Ubuntu 24.04 (Noble),
Xwayland fails to initialize hardware acceleration (GLAMOR) and falls
back to software rendering (llvmpipe/swrast).
This is caused by a regression in Mesa's AMDGPU device initialization
path:
1. Xwayland attempts to initialize GBM/GLAMOR on `/dev/dri/card1` (the primary
display node passed by mutter).
2. Mesa's `amdgpu_device_initialize` queries `AMDGPU_INFO_ACCEL_WORKING` using
the `DRM_IOCTL_AMDGPU_INFO` ioctl.
3. Because `/dev/dri/card1` is a primary display node and the client (Xwayland)
is unauthenticated (and Wayland has no mechanism to authenticate card nodes),
the kernel's DRM core rejects this query with -EACCES (-13) by design.
4. In Mesa 25.2.8, this failure is now treated as fatal, causing the entire
`amdgpu_device_initialize` call to abort.
5. In previous Mesa versions (such as 24.0.5), this query was either not run or
the failure was handled gracefully as non-fatal, allowing hardware acceleration
to initialize normally.
This regression forces all X11 applications and games (including those
running under Steam/Proton) to lose DRI3 support and fall back to
llvmpipe software rendering, causing them to crash on startup or suffer
severe performance loss.
WORKAROUND:
Downgrading all Mesa packages to 24.0.5-1ubuntu1 immediately restores
full hardware acceleration.
NOTE:
I attempted to report with `ubuntu-bug mesa` but received the error
`This report is about a package that is not installed.` Perhaps I should
file a separate bug report for `ubuntu-bug`?
** Affects: mesa (Ubuntu)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/2158711
Title:
Mesa 25.2.8 regression: amdgpu device initialize fails with EACCES
(-13) on primary card nodes for unauthenticated clients, breaking
Xwayland GLAMOR
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