It Looks Like AMD's Linux Developers Have Begun Work On Zen 2 / EPYC 2 "Rome" Support
Ahead of the Zen 2 processors expected in 2019, it appears AMD developers have begun working on their Linux kernel support patches for these next-generation CPUs. In particular, it appears the flow of Linux kernel code for supporting EPYC 2 "Rome" processors has begun.
Sent into the mainline Linux kernel this morning were the EDAC updates for Linux 4.20~5.0. EDAC in this context is for Error Detection And Correction - error reporting functionality mostly useful for server/workstation platforms. Usually the EDAC changes aren't worth writing about on Phoronix, but I did notice one of the changes standing out: "Add Family 17h, models 10h-2fh support."
That is building upon a previously reported patch for Model 11h "Great Horned Owl" support for EDAC, but now there are all these extra models added... When checking the latest model data, the later Family 17h Models up through 2Fh (47) are indeed for Zen 2. The patch itself for the AMD64 EDAC code is just adding the new models but with no real logic changes compared to Zen 1, thus no new architectural details are revealed by this new code.
With this being to the EDAC code, this is obviously more with server CPUs in mind, i.e. EPYC 2 (Rome), than for Ryzen desktop processors.
So far I haven't seen any other Linux kernel patches pertaining to these other Family 17h models aligned for Zen 2. Well, with this Linux kernel there is also initial xGMI support on the AMDGPU graphics driver side for Vega 20. It's also believed EPYC 2 platforms will support the xGMI interconnect but at this stage I haven't seen any xGMI Linux patches outside of the AMDGPU driver code.
The timing does make sense that we should begin seeing more Zen 2 enablement code landing soon. Especially on server platforms where customers don't tend to be running bleeding edge kernels, it's important to get that driver enablement support in place well ahead of the hardware's availability so it can be back-ported where appropriate to the enterprise/LTS kernels and all around stabilized and widely available by the time the new CPUs hit the shelves given the release cadence of the Linux kernel.
Anyhow, as any other Zen2/Rome patches come about to either the Linux kernel, GCC / LLVM compilers, or other software components, I'll certainly be writing about them as we look forward to the next-gen CPU launch in 2019.