Re: kern/40505: delay(9) is a MD non-interface

[Antti Kantee <pooka%iki.fi@localhost>]

On 19/07/14 01:00, Masao Uebayashi wrote:
>   For sys/kern/subr_prf.c:vpanic(), whose DELAY() is "I have nothing to
>   do", it can be replaced with MI function cpu_idle().  Question is, how
>   to implement it in rump.

cpu_idle() is not a MI function interface, from cpu.h:
#ifndef cpu_idle
void cpu_idle(void);
#endif

For that particular DELAY(), it might as well be "continue".

But to answer your question anyway: you can't meaningfully, rump kernels 
do not schedule threads onto cores (they run on threads which schedule 
cores), so "core is idle" does not make sense.

If you really have a strong use case for not spinning before reboot in 
case >1 cores panic, from the rump kernel perspective it is best to 
define a true interface, e.g. cpu_panicwait(), and call cpu_idle() in 
the kern_cpu.c implementation and sleep in a rump kernel.