Re: [RFC PATCH 2/2] kbuild: rust: use klint to provide CONFIG_FRAME_WARN

[Alexandre Courbot]

On Wed Jan 28, 2026 at 2:11 AM JST, Gary Guo wrote:
> From: Gary Guo <gary@xxxxxxxxxxx>
>
> klint is able to analyze frame size and warn on frames that are too big.
>
> With `register_tool(klint)` support, we can simply instruct rust to turn on
> `klint::stack_frame_too_large`. This is a no-op if normal rustc (or Clippy)
> is invoked, but will perform the check if klint is used.
>
> This is an example of a bug caught using this option:
>
> warning: stack size of `gsp::cmdq::Cmdq::new` is 8216 bytes, exceeds the 2048-byte limit
>    --> drivers/gpu/nova-core/gsp/cmdq.rs:453:5
>     |
> 453 |     pub(crate) fn new(dev: &device::Device<device::Bound>) -> Result<Cmdq> {
>     |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>     |
>     = note: the stack size is inferred from instruction `sub $0x2018,%rsp` at .text+32778

Initially this error puzzled me a bit since the objects directly built
by Cmdq::new are not larger than ~40 bytes, but then I dug into the
constructors it called and found that `PteArray`, a large struct, is
built on the stack! We need to convert it to an `Init` I guess.

Super valuable tool!