Re: nano: On Oldworld PowerPC, nano freezes machine when help is being displayed

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

>Re: lot of rebooting with manual fsck and the like: Been there, done that
>while debugging XFree86 4.0 on the Lombard. I'd try to get emergency sync
>going with SysRq, failing that I'd try to get as much info out of the
>crash by using serial console and hooking a panic() workalike to some
>trigger (special key if the keyboard interrupt is still working; do
>Powermacs have some sort of NMI interrupt switch??).

There is but it's not a real NMI, it is masked by cli().

I've been thinking about implementing a soft-disable mecanism based
on the OpenPIC interrupt priority mecanism, but it's tricky and
would slow things down significantly. Can still be a useful debugging
mecanism though as it would allow breaking via NMI on cli() lockups
and spin deadlocks.

Ben.