New AMD Linux Patch Acknowledges More Zen 5 CPU Models

Written by Michael Larabel in AMD on 24 April 2024 at 10:08 AM EDT. Add A Comment
A new AMD Linux kernel patch queued today via "x86/urgent" for routing into the Linux 6.9 development kernel expands the range of recognized CPU model IDs for upcoming Zen 5 processors.

AMD Linux engineers have been busy working on "Family 26" (1Ah) enablement that will serve at least for Zen 5 processors and potentially Zen 6 too if traditions hold. So far the Linux kernel has recognized AMD Family 26 CPUs with models from 0 to 15, 32 to 47, 64 to 79, and 112 to 127 model IDs as being Zen 5 processors. With the newly-posted patch, models 0x10 to 0x1f (16 to 31) are now treated as Zen 5 processors too.

AMD tends to reserve a much broader range of potential CPU model IDs than what is actually used in order to accommodate for future but currently unplanned processors, custom chip designs, etc. Many AMD Ryzen and EPYC processor SKUs also end up sharing the same CPU model IDs.

More Zen 5 models commit message

Meanwhile with the recently merged AMD Zen 5 (znver5) support for GCC it's treating all Family 26 CPUs with model IDs of 127 or less as Zen 5. Though if Zen 6 ends up sharing Family 26, that GCC handling is fine and ultimately will be adjusted once "znver6" support is introduced.

Long story short, today's patch in x86/urgent expands the range of CPU models AMD is treating as Zen 5 and the overall AMD Zen 5 Linux CPU enablement continues so that everything is hopefully in good shape for Linux use by the time the next-gen AMD Ryzen and EPYC processors are launched. The x86/urgent material is typically sent in each weekend to Linux Git, so expect this Zen 5 patch to be part of Linux 6.9-rc6 next Sunday.

When it comes to CPU Family/Model IDs and Linux, Intel's open-source engineers are finally preparing for the long-running end of Family 6.
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