Re: [PATCH v2 10/15] tools/rv: Add BPF monitors

[Gabriele Monaco <gmonaco@redhat.com>]

On Wed, 2026-10-21 at 13:12 +0200, Nam Cao wrote:
> Gabriele Monaco <gmonaco@redhat.com> writes:
> > On Wed, 2026-10-21 at 10:13 +0200, Nam Cao wrote:
> > > I wouldn't enable those by default though, it's way too much noises. As
> > > it's for debugging the model, we can have some sort of compile-time
> > > switch to turn it on.
> > 
> > That's almost what's happening already, in-kernel use tracepoints, gated by
> > static branches. Those are the closest thing you can get to a dynamic
> > compile-
> > time switch (assuming such a thing can exist), it's patching the code.
> 
> I was talking about how people are going to enable transition events,
> not how kernel enables them. Do we expose some user API for people to
> enable at run-time (and kernel can use run-time patching or whatever),
> or people enable them while compiling their BPF programs. I think the
> latter should suffice.

Everything BPF-related will need to go through the userspace tool. From loading
monitors to enabling things, but it shouldn't require any recompilation.

Right now I use only the -t flag (enable tracing and print to stdout), we'd need
some flag to only enable tracing.
After that you should be able to use ftrace as normal.

Gabriele