Re: [PATCH 00/11] Linux RISC-V trace framework and drivers

[Anup Patel]

On Thu, Oct 2, 2025 at 11:56 AM Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
>
> On Thu, Oct 02, 2025 at 11:37:21AM +0530, Anup Patel wrote:
> > This series adds initial support for RISC-V trace framework and drivers.
> > The RISC-V trace v1.0 specification is already ratified and can be found at:
> > https://github.com/riscv-non-isa/e-trace-encap/releases/tag/v1.0.0-ratified
> > https://github.com/riscv-non-isa/tg-nexus-trace/releases/tag/1.0_Ratified
> >
> > The RISC-V trace framework and drivers are designed to be agnostic to the
> > underlying trace protocol hence both RISC-V E-trace and RISC-V N-trace should
> > work fine. The discovery of trace protocl parameters are left to user-space
> > trace decoder.
> >
> > In ther future, there will be subsequent series adding:
> > 1) Sysfs support
>
> why does "trace" need sysfs support?  No other cpu platform uses that
> today, so why is a new user/kernel api needed?

We saw trace support for other architectures (e.g. ARM coresight) allowing
trace start/stop through sysfs. If this is an obsolete or not preferred approach
then we will deprioritize and possibly never add it.

Regards,
Anup