[PATCH 0/3] printk: Add force_early_printk boot param

[Peter Zijlstra]

Most all printk() bits are terminally broken because they rely on the scheduler
and blocking locks to function, making them unsuitable for debugging the
scheduler and NMI context things.

Luckily many early_printk implementations are relatively sane and don't rely on
anything much at all; the x86 early_serial_console for example is pure
bit-banging without anything.

So provide means to always use these and avoid the whole printk mess.