Mesa 20.3 Supports Intel Alder Lake Gen12 Graphics
Given that Alder Lake is using Intel Xe "Gen12" graphics as found already for Tiger Lake and Rocket Lake, the actual driver-side enablement is quite minimal thanks to employing the existing code paths. The Alder Lake "ADL-S" support was merged into Mesa on Tuesday and is just 20 lines of new code. That consists of just adding the new PCI IDs and then the family bits for the Alder Lake family and indicating they make use of Gen12 features.
The Alder Lake S graphics PCI IDs added are 0x4680, 0x4681, 0x4682, 0x4683, 0x4690, 0x4691, 0x4692, 0x4693, 0x4698m and 0x4699. But as always the PCI ID count doesn't necessarily mean much as some of those IDs may be reserved for engineering samples / pre-production models or for possible future but currently unplanned variants.
So this code adding Alder Lake support to Mesa for their Iris Gallium3D (OpenGL) and ANV (Vulkan) will be part of Mesa 20.3 that will be out as stable in December. But you'll still need the kernel support which won't come until Linux 5.11 as stable in early 2021. With Alder Lake not expected until H2'2021, there still is sufficient time for getting this open-source support out there.