Mesa 26.0.0‑rc3 adds driver‑level fixes—most notably tighter BVH handling in radv and internal AV1 tile calculations in ANV—while polishing LLVM‑22 compatibility across the stack. Early testers have already spotted “device lost” crashes on older AMD GPUs, which the new BVH patches aim to eliminate, but software rasterizer builds with LLVM‑22 can still hit shader compilation errors. Building the candidate in a separate directory and installing it under a user‑local prefix lets you trial the changes without overwriting your system Mesa packages. 

Mesa 26.0.0‑rc3 release: what’s new, what to watch for, and how to give it a spin

The third release candidate of Mesa 26.0.0 landed today. It brings a handful of driver tweaks, a few Vulkan clean‑ups, and the usual assortment of compiler‑level adjustments. If you run a Linux desktop that leans on OpenGL or Vulkan, this article explains the headline changes, points out where trouble has already surfaced, and shows how to test the RC without blowing up your main system.

Quick rundown of the most visible changes

• Radeon/Vulkan (radv) gets tighter BVH handling – NaNs are stripped from acceleration structures, LBVH invocations are capped, and internal nodes collapse when possible. The net effect is a modest boost in ray‑tracing stability on recent AMD GPUs.
• Intel ANV AV1 work – Tile positions are now computed internally; the encoder remains disabled on platforms that haven’t been validated yet. Expect smoother playback of AV1 streams on supported hardware, but don’t expect to start encoding anything just yet.
• Broadcom V3D driver bumps the generation version – A quiet change that mainly clears up some lingering compatibility warnings in the logs.
• LLVM‑22 support across several components – The CLC front‑end and a few nir passes were patched to compile cleanly with LLVM 22, which many distros are already shipping as default.
• A handful of CI clean‑ups – Erroneous skips removed from the Lima tests, stale xfails cleared in the test‑suite, and some header reorderings that stop compilation errors on exotic toolchains.

These aren’t headline‑grabbing features, but they collectively tighten the ship before the final 26.0.0 release.

Known rough edges

A few users reported occasional crashes in games that use Vulkan ray tracing on older AMD cards after pulling an earlier RC. The crash manifested as a “device lost” error right after the first frame of a ray‑traced scene. The radv patches above were introduced specifically to stop that, but the fix only applies when the driver can actually collapse BVH nodes – older silicon may still hit the bug. If you’re on an R9 290 or similar, keep the stable 25.x series until the final passes its smoke tests.

Another quirk shows up in Mesa’s software rasterizer (llvmpipe) when paired with LLVM‑22: some shader compilation paths emit warnings that later turn into hard errors under heavy load. The workarounds are to either force the use of an older LLVM version or drop back to a non‑RC Mesa build for now.

How to try the RC without breaking your main desktop

1. Grab the tarball –

   wget https://mesa.freedesktop.org/archive/mesa-26.0.0-rc3.tar.xz
   sha256sum mesa-26.0.0-rc3.tar.xz
   

   Verifying the sha256 checksum (c0010fb19bb525ffcedab0d00f4d0430471e6342b86041ff3358142a96ae50d6) prevents a corrupted download from wrecking your build.

2. Extract and create a clean build directory –

   tar xf mesa-26.0.0-rc3.tar.xz
   mkdir mesa-build && cd mesa-build
   

   Building in a separate folder keeps the source tree pristine, which helps when you need to switch back.

3. Configure with meson – For most users the default options are fine, but it’s worth explicitly disabling drivers you don’t use to speed up compilation:

   meson setup .. \
   -Dgallium-drivers=radeonsi,swrast,virgl \
   -Dvulkan-drivers=radv,anv \
   -Dllvm=enabled \
   -Dshared-llvm=disabled
   

   Disabling unused drivers reduces build time and memory pressure on modest laptops.

4. Compile –

   ninja -C .
   

   The -j$(nproc) flag is implied; if you’re on a 4‑core laptop, the compile will finish in roughly an hour.

5. Install into a sandbox location – Avoid overwriting the system Mesa packages:

   DESTDIR=$HOME/mesa-rc3 ninja install
   

   This drops the libraries under $HOME/mesa-rc3/usr/lib, leaving the distro’s version untouched.

6. Tell your session to use the new build – Add a wrapper script or export LD_LIBRARY_PATH before launching an application:

   export LD_LIBRARY_PATH=$HOME/mesa-rc3/usr/lib:$LD_LIBRARY_PATH
   glxinfo | grep "OpenGL version"
   

   If the output shows “Mesa 26.0.0‑rc3”, you’re running the candidate.

7. Run a quick sanity check – Launch something lightweight that uses OpenGL (e.g., glxgears) and then a Vulkan demo (vkcube). Watch for immediate crashes or “device lost” messages; those indicate a regression that should be filed on the Mesa issue tracker.

When you’re done, simply close the terminal or unset LD_LIBRARY_PATH. Your normal desktop will revert to the distro’s stable Mesa version.

Should you stick with the RC?

If you’re a developer chasing the newest Vulkan extensions or you run a fresh AMD GPU that benefits from the BVH tweaks, testing the RC makes sense. For most everyday users – especially those on older hardware or on laptops where driver stability is critical – staying on the current stable branch (25.x) remains the safest bet. The Mesa team is still polishing 26.0.0; a few more release candidates will follow before they call it final.

Give it a whirl if you’re comfortable building from source, and don’t forget to file any crashes with as much log detail as possible. The community thrives on those reports.