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SubjectRe: [RFC PATCH 0/6] Support raw event and DT for perf on RISC-V
On Mon, Jun 29, 2020 at 8:49 AM Zong Li <> wrote:
> This patch set adds raw event support on RISC-V. In addition, we
> introduce the DT mechanism to make our perf more generic and common.
> Currently, we set the hardware events by writing the mhpmeventN CSRs, it
> would raise an illegal instruction exception and trap into m-mode to
> emulate event selector CSRs access. It doesn't make sense because we
> shouldn't write the m-mode CSRs in s-mode. Ideally, we should set event
> selector through standard SBI call or the shadow CSRs of s-mode. We have
> prepared a proposal of a new SBI extension, called "PMU SBI extension",
> but we also discussing the feasibility of accessing these PMU CSRs on
> s-mode at the same time, such as delegation mechanism, so I was
> wondering if we could use SBI calls first and make the PMU SBI extension
> as legacy when s-mode access mechanism is accepted by Foundation? or
> keep the current situation to see what would happen in the future.
> This patch set also introduces the DT mechanism, we don't want to add too
> much platform-dependency code in perf like other architectures, so we
> put the mapping of generic hardware events to DT, then we can easy to
> transfer generic hardware events to vendor's own hardware events without
> any platfrom-dependency stuff in our perf.

Please re-write this series to have RISC-V PMU driver as a regular
platform driver as drivers/perf/riscv_pmu.c.

The PMU related sources will have to be removed from arch/riscv.

Based on implementation of final drivers/perf/riscv_pmu.c we will
come-up with drivers/perf/riscv_sbi_pmu.c driver for SBI perf counters.


> Zong Li (6):
> dt-bindings: riscv: Add YAML documentation for PMU
> riscv: dts: sifive: Add DT support for PMU
> riscv: add definition of hpmcounter CSRs
> riscv: perf: Add raw event support
> riscv: perf: introduce DT mechanism
> riscv: remove PMU menu of Kconfig
> .../devicetree/bindings/riscv/pmu.yaml | 59 +++
> arch/riscv/Kconfig | 13 -
> arch/riscv/boot/dts/sifive/fu540-c000.dtsi | 13 +
> arch/riscv/include/asm/csr.h | 58 +++
> arch/riscv/include/asm/perf_event.h | 100 ++--
> arch/riscv/kernel/Makefile | 2 +-
> arch/riscv/kernel/perf_event.c | 471 +++++++++++-------
> 7 files changed, 471 insertions(+), 245 deletions(-)
> create mode 100644 Documentation/devicetree/bindings/riscv/pmu.yaml
> --
> 2.27.0

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