Linux 5.18 EDAC Continues Making Preparations For AMD Zen 4
The Linux 5.17 AMD EDAC changes included adding support for Registered DDR5 (RDDR5) and Load-Reduced DDR5 (LRDDR5) system memory and adding in support for new Family 19h models.
With Linux 5.18 there is more AMD EDAC work still focused around these new AMD Family 19h models. There has been some disagreeing with my assessment that AMD Zen 4 will still be Family 19h, but the patch work continues to be pointing to that being the case. Zen 4 looks like it will be in Family 19h -- the same as Zen 3 -- and similar to how Zen / Zen+ / Zen 2 spanned Family 17h.
While these patches do not spell out Zen 4, these model IDs don't match existing AMD CPUs including the newly released and exciting Milan-X parts. The AMD EDAC changes for Linux 5.18 add the ability to set the memory type per DIMM -- not for say DDR5 and DDR4, but the likes of LRDDR5 / DDR5 / RDDR5 memory types across different memory controllers. The other work is setting a new "family flags" bitmask and using new offsets for AMD Family 19h Model 10h. A new bitfield is added for indicating DDR5 memory use on a memory controller.
The Linux kernel continues preparing AMD code paths around DDR5 support for next-generation platforms.
Besides the EDAC work, there has been thermal monitoring and other additions in recent and ongoing kernels ahead of AMD's next-gen hardware launches. See the EDAC pull request for more details on the changes that were merged on the Error Detection and Correction front for Linux 5.18.