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authorYijie Yang <yijie.yang@oss.qualcomm.com>2026-08-11 16:46:47 +0800
committerRob Herring (Arm) <robh@kernel.org>2026-08-15 15:46:52 -0500
commite1c13aed4a1641550e8c9518c96f016e1d52d09b (patch)
tree61c2297688373db165cc857b7c7adcb147a5c419 /tools/lib/perf/TODO
downloadlinux-stable-e1c13aed4a1641550e8c9518c96f016e1d52d09b.tar.gz
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dt-bindings: interconnect: qcom-bwmon: Add Maili cpu-bwmon compatiblegrafted
Add the Qualcomm Maili SoC compatible string for the CPU bandwidth monitor (BWMONv4). This falls back to the sdm845-bwmon compatible, consistent with the existing pattern used by other recent SoCs such as sm8750 and kaanapali. Signed-off-by: Yijie Yang <yijie.yang@oss.qualcomm.com> Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com> Reviewed-by: Jingyi Wang <jingyi.wang@oss.qualcomm.com> Link: https://patch.msgid.link/20260811-bwmon-v2-1-80f7f150ab9e@oss.qualcomm.com Signed-off-by: Rob Herring (Arm) <robh@kernel.org>
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+Future ABI changes
+==================
+
+This file collects items that require a libperf ABI bump. Each entry
+should describe the current limitation, the desired end state, and the
+scope of the change so that a future ABI revision can batch them
+together.
+
+1. Widen struct perf_cpu.cpu from int16_t to int
+ - Current limit: 32767 CPUs. No architecture exceeds this today
+ (x86_64 max is 8192, arm64 is 4096), but NR_CPUS limits keep
+ growing. perf clamps to INT16_MAX in set_max_cpu_num() as a
+ safety net.
+ - Code simplification: the int16_t forces defensive truncation
+ checks at every boundary where a wider CPU index (int from
+ sample->cpu, al->cpu, etc.) is narrowed into struct perf_cpu.
+ Without these checks, values > 32767 silently wrap to negative
+ numbers (two's complement), bypassing bounds validation.
+ Widening to int eliminates this entire class of silent
+ truncation bugs and removes the need for the INT16_MAX clamp
+ in set_max_cpu_num().
+ - Scope: struct perf_cpu is embedded everywhere — perf_cpu_map__cpu(),
+ perf_cpu_map__min(), perf_cpu_map__max(), perf_cpu_map__has(), the
+ for_each_cpu macros, and all internal callers. The perf_cpu_map
+ internal array (RC_CHK_ACCESS(map)->map[]) stores struct perf_cpu
+ directly. Widening changes the struct layout and every function
+ that returns or accepts struct perf_cpu by value.
+ - Migration: bump LIBPERF version in libperf.map, audit all
+ sizeof(struct perf_cpu) assumptions, update perf.data
+ serialization if needed.