Re: [PATCH 08/16] tracetool: Add Rust format support

[Stefan Hajnoczi <stefanha@gmail.com>]

On Thu, Sep 25, 2025 at 8:40 AM Paolo Bonzini <pbonzini@redhat.com> wrote:
>
> On 9/25/25 13:50, Stefan Hajnoczi wrote:
> > On Wed, Sep 24, 2025 at 09:58:04PM +0200, Paolo Bonzini wrote:
> >> On Wed, Sep 24, 2025, 20:10 Stefan Hajnoczi <stefanha@redhat.com> wrote:
> >>
> >>>> fn trace_event_state_is_enabled(dstate: u16) -> bool {
> >>>>       unsafe { trace_events_enabled_count } != 0 && dstate != 0
> >>>> }
> >>>
> >>> The generated code is missing DTrace's SDT semaphore (see
> >>> generate_h_backend_dstate() in scripts/tracetool/backend/dtrace.py). The
> >>> conditional must be taken when a tool like SystemTap or GDB sets the SDT
> >>> semaphore. Right now it will not be taken because the conditional only
> >>> looks at _ ## id ## _DSTATE and not the SDT semaphore.
> >>>
> >>
> >> This is private code to trace-*.rs, for use within the tracepoint functions
> >> only; it's not a public "is the tracepoint active" API. The public side in
> >> C does look at the semaphore.
> >
> > You're right, the code is fine just with the function renamed.
>
> No problem---in fact I have now realized that, for systemtap, I have to
> ensure that the semaphore is shared between C and Rust!

Is anyone working on the DTrace support? If not, I'll keep it in mind
in case I get some time over the next few weeks.

Stefan