AMD Radeon RX 6700 XT Linux Performance
The Radeon RX 6700 XT is represented as the "Navy Flounder" when it comes to the Linux driver support. AMD will be releasing an updated Radeon Software for Linux packaged driver with the RX 6700 XT driver for those preferring to go that route and are running a supported enterprise Linux distribution where that packaged driver is compatible. So for those users, you should be in good shape once that packaged driver is published today or in the coming days. One unfortunate detail is that the Vulkan ray-tracing support is still not enabled with the Radeon Software for Linux driver but is said to be coming with the 21.10 release stream that should be appearing next. Similarly, the open-source RADV and AMDVLK Vulkan drivers do not yet support the Vulkan ray-tracing extensions, but then again there isn't much in the way of Vulkan RT usage on Linux besides a few tech demos. VKD3D-Proton at least is making progress on DirectX 12 DXR over Vulkan so moving forward that will become the likely path for ray-traced Linux gaming with Steam Play running modern Windows games on Linux.
When it comes to upstream open-source driver support for the Radeon RX 6700 XT, it remains the usual case of: the newer, the better. The Radeon RX 6700 XT review sample I received from AMD was working fine on Linux 5.11+ and was using Mesa 21.1-devel though Mesa 20.0 and potentially 19.3 should work too. However, in the case of new GPUs especially and with the RadeonSI and RADV Mesa drivers continuing to rapidly advance, with a new GPU family you really want to be using the latest stable or development builds for the best features and performance. The benchmarks in this article were running on Mesa 21.1-devel with Linux 5.12 Git, but Linux 5.11 stable was thoroughly tested too with good success.
Mesa 21.1-devel via the Oibaf PPA was in good shape for the Radeon RX 6700 XT. The only driver issue I initially ran into was some on-screen corruption, but that Navy Flounder bug has been fixed by this merge request.
So long story short, even using the latest stable kernel/Mesa users should be in good shape if not wanting to run (or not on a supported distribution) for handling the Radeon Software for Linux package but the best experience/performance is still when using Git. One annoying aspect that remains to be the case is AMD hasn't yet published the Navy Flounder firmware needed for initialization with the AMDGPU kernel driver. That Navy Flounder firmware/microcode should appear today in linux-firmware.git so it can work its way out to the Linux distributions. For my testing I just extracted it from their packaged driver. Those blobs are needed for any level of accelerated open-source support, so make sure you pick that firmware up from the Git tree or updated distribution packages if you get your hands on a Radeon RX 6700 XT soon.
AMD seems to still be apprehensive about publishing their GPU microcode prior to hardware launch, presumably to prevent anyone from poking at them for trying to infer any hardware details prior to being announced. So it does make for this annoying situation of Linux users needing to scramble to ensure their system has Navy Flounder microcode images present on their system in order for the open-source driver support to work. It's not nearly as bad as having to worry about building a Linux kernel (or Mesa) from a Git tree or GPU support only found in branched/patch form like has often been the case in the distant past, but just an unfortunate obstacle users have to deal with if wanting to be an early AMD customer of new graphics cards on Linux.
In any case, if you've been through this dance before, it's easy to get going with the Radeon RX 6700 XT on Linux.