[BUG] Threaded printk breaks early debugging

[Peter Geis]

Good Morning,

First, I love this patch from a functional standpoint! However I've
run into an issue debugging early boot issues. Anything that causes
the kernel threading system to die (for example here, a NPE) causes
the boot console to halt before it outputs the error.

Would it be possible to have both a kconfig option and a runtime
option to toggle printk_fallback_preferred_direct()? Currently I've
had to force it at all times while debugging.

Thanks again for this amazing work!

Very Respectfully,
Peter Geis