Hi Ben, On 27/08/2025 09:53, Ben Horgan wrote: > On 8/22/25 16:29, James Morse wrote: >> The bulk of the MPAM driver lives outside the arch code because it >> largely manages MMIO devices that generate interrupts. The driver >> needs a Kconfig symbol to enable it, as MPAM is only found on arm64 >> platforms, that is where the Kconfig option makes the most sense. >> >> This Kconfig option will later be used by the arch code to enable >> or disable the MPAM context-switch code, and registering the CPUs >> properties with the MPAM driver. >> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig >> index e9bbfacc35a6..658e47fc0c5a 100644 >> --- a/arch/arm64/Kconfig >> +++ b/arch/arm64/Kconfig >> @@ -2060,6 +2060,23 @@ config ARM64_TLB_RANGE >> ARMv8.4-TLBI provides TLBI invalidation instruction that apply to a >> range of input addresses. >> >> +config ARM64_MPAM >> + bool "Enable support for MPAM" >> + help >> + Memory Partitioning and Monitoring is an optional extension >> + that allows the CPUs to mark load and store transactions with >> + labels for partition-id and performance-monitoring-group. >> + System components, such as the caches, can use the partition-id >> + to apply a performance policy. MPAM monitors can use the >> + partition-id and performance-monitoring-group to measure the >> + cache occupancy or data throughput. >> + >> + Use of this extension requires CPU support, support in the >> + memory system components (MSC), and a description from firmware >> + of where the MSC are in the address space. >> + >> + MPAM is exposed to user-space via the resctrl pseudo filesystem. >> + >> endmenu # "ARMv8.4 architectural features" > Should this be moved to "ARMv8.2 architectural features" rather than the > 8.4 menu? In the arm reference manual, version L.b, I see FEAT_MPAM > listed in the section A2.2.3.1 Features added to the Armv8.2 extension > in later releases. Hmmm, I don't think we've done that anywhere else. I'm only aware of one v8.2 platform that had it, and those are not widely available. As it was a headline v8.4 feature I'd prefer to keep it there. I think its more confusing to put it under v8.2! Thanks, James
