On Wed, Mar 22, 2017 at 04:27:50PM -0300, Guilherme G. Piccoli wrote:
> The xmon parameter nobt was added long time ago, by commit 26c8af5f01df
> ("[POWERPC] print backtrace when entering xmon"). The problem that time
> was that during a crash in a machine with USB keyboard, xmon wouldn't
> respond to commands from the keyboard, so printing the backtrace wouldn't
> be possible.
>
> Idea then was to show automatically the backtrace on xmon crash for the
> first time it's invoked (if it recovers, next time xmon won't show
> backtrace automatically). The nobt parameter was added _only_ to prevent
> this automatic trace show. Seems long time ago USB keyboards didn't work
> that well!
Xmon still can't use a USB keyboard. It's not a question of how well
USB keyboards work, it's that having a non-interrupt-driven USB stack
with (at least) an OHCI host controller driver and a keyboard driver
in xmon is impractical.
Paul.
