Radeon Navi 12/14 Open-Source Driver Support Now Being Marked As "Experimental"
Written by Michael Larabel in Radeon on 17 September 2019 at 04:46 PM EDT. 6 Comments
RADEON --
In an interesting change of course, the open-source driver support for AMD Radeon Navi 12 and Navi 14 GPUs is being flagged as experimental and hidden behind a feature flag.

Back at the start of August AMD sent out their AMDGPU Linux kernel driver support for Navi 12 along with Navi 14. That Navi 12/14 support has since been queued up for introduction in the Linux 5.4 kernel along with the new Vega-based Arcturus GPU.

Somewhat surprising, with the code on its way to the mainline Linux 5.4 kernel this week and already out for the past month and a half, only now the Navi 12/14 support is to be hidden behind the driver's "experimental" feature flag. In marking that support as experimental, the support isn't enabled by default but requires the amdgpu.exp_hw_support=1 kernel module parameter to be set at boot (or driver load) time. Normally when the Intel and AMD Linux graphics drivers are hiding hardware support behind a feature flag over the preliminary state, they normally are doing so from the very beginning, not weeks later.

The patch for moving Navi 12/14 as experimental for Linux 5.4 simply carries the message, "We can remove this later as things get closer to launch."

Presumably moving this Navi 12/14 support behind the experimental flag is being done due to bugs coming up in the driver that warrant not enabling the support by default. We have heard that Navi 14 is buggy with NGG (Next-Gen Geometry) though it seems unlikely the kernel driver would block the support over that condition with the OpenGL/Vulkan drivers able to just use their legacy (non-NGG) path. But with Navi 12/14 being unreleased products, we're unlikely to hear anything more about the reasoning until launch.

This hiding of the support behind the feature flag until "closer to launch" also raises the potential the Navi 12/14 introduction could be further away than some would hope. The Linux 5.4 kernel cycle just opened this past Sunday and Linux 5.4 won't be out as stable until November. AMD could always drop the experimental flag with fixes closer to launch or depending upon the changes needed to polish Navi 14/15 could end up having to wait until Linux 5.5 (entering development in November, releasing as stable in early 2020), but whatever the case we'll see how this situation plays out and cross our fingers for a smooth Navi 12/14 launch for Linux gamers and the like.

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Michael Larabel is the principal author of Phoronix.com and founded the site in 2004 with a focus on enriching the Linux hardware experience. Michael has written more than 10,000 articles covering the state of Linux hardware support, Linux performance, graphics drivers, and other topics. Michael is also the lead developer of the Phoronix Test Suite, Phoromatic, and OpenBenchmarking.org automated benchmarking software. He can be followed via Twitter or contacted via MichaelLarabel.com.

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