Re: [PATCH RFC 00/11] rust: add support for dynamic debug

[Zhi Wang <zhiw@nvidia.com>]

On Tue, 20 Oct 2026 19:30:33 +0200
Thomas Weißschuh <linux@weissschuh.net> wrote:

> +To: Zhi Wang
> 

Thanks Alex for bridge the threads together!

Hey Thomas,

Thanks for the comparison! As a user of this feature, I'm happy to
combine the two series and see this making progress.

The Bounded types, bitfield tests, and module_path!() fallback look
like useful additions. One clarification: with CONFIG_JUMP_LABEL, our
disabled path already has no FFI call. static_branch_unlikely!() is
sufficient for our initially disabled callsites, including enabling
them at runtime.

For the combined series, I'd like to retain these behaviors:

- Debug logging is independent of debug_assertions, starts disabled,
  and is controlled through dynamic debug. IMHO, fewer distro kernels
  are compiled with CONFIG_RUST_DEBUG_ASSERTIONS=y nowadays. (At least,
  Arch and Fedora are compiled with N)

- Disabled pr_debug!()/dev_dbg!() calls do not evaluate their
  arguments. IMHO, it seems the current dev_dbg!() in your patch
  evaluates the params before checking the switch on/off. (pr_debug()!
  looks fine though)

- The dynamic-debug prefix flags remain supported. (I use the C version
  of dynamic debug to support e.g. +m, +l and _t)

Could you share your pending encapsulation/Opaque and static-branch
wip patches? We can then work out how they fit together, incorporate
Alice's review feedback, and preserve attribution for Andrew's work.

Thanks,
Zhi.

> Hi Alexandre,
> 
> On 2026-10-20 22:14:12+0900, Alexandre Courbot wrote:
> > On Sun Oct 11, 2026 at 9:52 PM JST, Thomas Weißschuh wrote:  
> > > Add the Rust infrastructure to integrate with the dynamic debug
> > > infrastructure.
> > >
> > > Static keys are not used for now, as the full bindings are missing
> > > for those. A follow-up series will add that.
> > > Also custom classes are not supported yet, but could be added on
> > > top.
> > >
> > > Patches 1-4: Generic Rust preparation patches.
> > > Patches 5-7: C dynamic debug preparation patches.
> > > Patches 8: Rust Dynamic debug infrastructure.
> > > Patches 9-11: Rust Dynamic debug enablement.  
> > 
> > Were you aware of this series [1]?  
> 
> I was was told about the original work from Andrew back at Kangrejos.
> However I was unable to find it on LKML and it was not clear how far
> along that series has come along. The posting of Zhi's v3 only
> happened after I started on my variant, and I did not see it until
> you mentioned it. So my development is completely independent from
> Andrew's and Zhi's.
> 
> > There seems to be quite a bit of overlap.  
> 
> Indeed. I see pros for both serieses:
> 
> Mine:
> * No FFI in the fastpath.
> * No need for RUST_MODNAME.
> * Use of Bounded.
> * Tests for the flag encoding.
> * modname!() as function name.
>   (As discussed with Benno and Gary and LPC)
> * Better encapsulation of 'struct Descriptor' (partially not yet
> posted)
> * Use of Opaque<> to wrap bindings::_ddebug (not yet posted).
> * Use of !cv() (not yet posted).
> 
> Andrew/Zhi:
> * Better docs.
> * Static branch support.
>   * static_branch_likely!() support is missing however.
>   * I also have follow-up patches to enable static_branch_likely!().
> * host doctest support.
> 
> I am perfectly fine with merging both serieses.
> 
> 
> Thomas
> 
> > [1]
> > https://lore.kernel.org/all/20261001145940.1077801-1-zhiw@nvidia.com/
> >