Mesa 3D lands on AmigaOS 4 with a serious Radeon performance boost

AmigaOS 4 has gained a much more capable 3D graphics option with a native, hardware-accelerated port of Mesa 3D. Based on Mesa 26.1.5, it brings support for OpenGL up to version 4.6 and OpenGL ES 3.2, along with familiar Mesa technologies such as Gallium, RadeonSI, NIR and the ACO shader compiler. That’s a big technical step. The port was developed by kas1e and is aimed at both users who want to run more demanding 3D software and developers who need a more modern OpenGL environment on AmigaOS 4. And it’s 100% free!

Mesa talks directly to Radeon hardware

One of the most interesting parts of this release is how Mesa reaches the graphics card. Instead of running through ogles2.library and Warp3D Nova, the new implementation connects directly to the RadeonHD and RadeonRX driver layer. That gives Mesa’s own graphics components much more direct access to the GPU.

In practical terms, there are fewer layers sitting between an OpenGL application and the graphics hardware. The package includes a native mesa.library that can serve both OpenGL and OpenGL ES programs. It can also handle multiple applications using the graphics system at the same time, which makes it useful as a general graphics layer rather than something built around one particular piece of software.

Getting Mesa running on AmigaOS 4 wasn’t simply a matter of compiling the existing source code, though. The platform’s PowerPC hardware uses big-endian data handling, while much of modern graphics development assumes little-endian systems.

The port therefore includes a long list of endian fixes covering vertex data, graphics formats, index handling and other GPU-related operations. It also adds PPC32 assembly routines and AmigaOS-specific threading code built around Exec and DOS.

Modern shader support changes the picture

Shaders are another major part of the release. Mesa for AmigaOS 4 includes NIR and the ACO shader compiler, while avoiding the need for LLVM. That gives the graphics stack a modern way to process and compile shaders for supported Radeon cards without bringing in another very large dependency. This matters when software starts using more advanced OpenGL features.

Older AmigaOS 4 graphics solutions could run into limits with complicated shaders, particularly when programs demanded more GPU registers or relied on newer rendering techniques. Mesa gives developers access to a graphics architecture built with modern programmable GPUs in mind.

The port also supports features such as GPU fences, asynchronous command submission, cache handling and presentation. GART memory is used when the installed Radeon driver and graphics card support it. Systems without suitable GART support can still run Mesa, although they’ll fall back to another memory path that may be slower.

Early benchmarks show useful gains

Compatibility is only part of the story. Performance has improved too. One Quake 3 test, using the same settings in both builds, reached 125 frames per second through GL4ES. The Mesa version managed 155 frames per second. That’s a noticeable jump.

Shader-heavy workloads can show even larger differences. Some tested shaders reportedly run two, three or even four times faster through Mesa. Programs that previously failed because their shaders wouldn’t compile may also have a better chance of working with the new stack.

Of course, the graphics card still matters. Among the tested RadeonRX cards, the Radeon RX 580 based on Polaris 10 delivered the best performance. On the RadeonHD side, the Radeon R9 280X with a Tahiti GPU came out on top.

Several AmigaOS 4 systems have already been tested

The hardware testing covers a decent spread of AmigaOS 4 machines. Mesa has been tested on the AmigaOne X1000, AmigaOne X5000, Sam460 and Pegasos2 using a PCI-to-PCI Express bridge. RadeonHD testing includes Oland, Cape Verde, Pitcairn and Tahiti GPUs, while RadeonRX testing covers Polaris 10, Polaris 11 and Polaris 12.

Specific cards tested include the Radeon R7 240, R7 250, R9 280, RX 550, RX 560, RX 570 and RX 580. You’ll need AmigaOS 4.1 FE 3 along with compatible Radeon drivers. RadeonRX 2.12 and RadeonHD 5.20 are the recommended versions. RadeonHD 3.7 can still be used, but there’s a catch. Its lack of suitable GART support can reduce performance significantly on some machines.

Developers get an SDK too

This isn’t just a runtime library. The roughly 17 MB package also includes an SDK, so developers can start building or adapting OpenGL software specifically for the new Mesa environment. That’s likely to be one of the most useful parts of the release over time.

There are testing tools in the package as well, including Shadertoy examples and the glmark2 graphics benchmark. A Radeon information utility is included for checking installed RadeonHD and RadeonRX hardware.

Development isn’t finished either. Planned work includes an on-disk shader cache, more endian fixes, bug fixes and further optimisation. For AmigaOS 4, Mesa 26.1.5 opens up a much wider OpenGL feature set than users have had before. It brings direct Radeon access, OpenGL 4.6, modern shader compilation and a full SDK into one package. For developers especially, that’s the key point. There’s now a much more capable base for building and porting modern 3D software on AmigaOS 4.

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