lindebugfs: Add `debugfs_create_str()`

[dumbbell]

Summary

This function is used by the i915 DRM driver starting with Linux 6.8.

This is part of the update of DRM drivers to Linux 6.8.

Sponsored by: The FreeBSD Foundation

[bz]

sys/compat/lindebugfs/lindebugfs.c

645

To my understanding this is not going to work.

simple_attr_read uses a 24 byte buffer. That's going to overflow for (assumed) most strings.
Also the default write routine will try to convert the string to a number using strtoq in the end.

[dumbbell]

sys/compat/lindebugfs/lindebugfs.c

645

You are right, I didn’t look at the implementation of DEFINE_DEBUGFS_ATTRIBUTE() and assumed something more involved :-) I will rework the patch.

[dumbbell]

Reimplement patch entirely

It depends on D49374.