The ARM64 (AArch64) architecture updates have been submitted ahead of the imminent Linux 6.17 merge window.
One of the new features coming for ARM64 in this next version of the Linux kernel is enabling BRBE support within the Linux kernel’s perf subsystem. BRBE is short for the Branch Record Buffer Extension and has been part of the Arm ISA spec the past five years. The Branch Record Buffer Extension allows for capturing a recent sequence of branches for low-compute and low-memory overhead capture/analysis for tracing/debug purposes. Tied into the Linux perf subsystem should be useful for low overhead profiling of AArch64 systems.
More details on Arm BRBE can be found in this Linaro presentation from 2020.
Linux 6.17 for ARM64 also brings initial BBML2 support within the contpte_convert() code as a TLBI optimization for AArch64 CPUs that do not require break-before-make when changing the user PTEs between contiguous and non-contiguous.
There is also PMU support for new HiSilicon SLLC and DDRC v3 hardware, support for MTE store-only checking with FEAT_MTE_STORE_ONLY, forcing VMAP_STACK always-on, and other low-level code improvements. More details via this pull request for the Linux 6.17 merge window.
