It's easy to check (unless the kernel was compiled without config in procfs, which it probably wasn't):

  $ zgrep CONFIG_DRM_PANIC_SCREEN_QR_CODE /proc/config.gz
  CONFIG_DRM_PANIC_SCREEN_QR_CODE=y

I suspect it's more of a 'this would be handy to have, and I would prefer to use rust' as opposed to motivated by making the language harder to do without in the kernel. Certainly this kind of thing I would find rust much nicer for than C.

(I would agree the first argument is kinda wavy. If anything the panic handler has a fairly unique relationship with memory safety: it's likely to be executing in an environment where that's already gone out the window and it needs to try to assume as little as possible about what might or might not be correct that its reading from and writing to, while also its own memory safety is perhaps less critical because the system is already crashing, it's just got to get the info out before everything completely stops. Though that doesn't make it immune from security concerns. A code execution vulnerability in the handler means any panic could turn into a worse problem)

The first version of the PR is a little more honest: https://patchwork.freedesktop.org/series/135886/

> There is no particular reason to do it in rust, I just wanted to learn rust, and see if it can work in the kernel.

Which I think is fairer. Good on her for trying to stay on top of recent developments. With Linux basically supporting Rust now so it's a valid choice, especially for a new component. Plus, it's not like this is an important features, the anti-Rust people can live perfectly fine without QR code crash dumps like they have for decades now.

I think doing this in C is an unnecessary risk (you really don't need all that many raw pointer interactions and shared struct ownership) but the security and stability of this component hardly matters. The kernel is already dead because of a bug or a hardware failure anyway, this is just making the catastrophic failure of the rest of the system a bit prettier.

What's the need for memory safety if the kernel is going to stop executing and memory will be wiped before any further execution is done.

It may isn't useful for you but a huge majority has a phone they can use for this task.