writing ktrace output to serial port

[Eugene Grosbein]

Hi!

I'm trying to debug kernel panic in 4.10-STABLE.
It is 100% repeatable in my environment but this environment is very
customized and it would be hard for others to reproduce it in my way
(this includes non-standard build of libvgl and mplayer and his libs).

So I want to see what is happening just before my mplayer crashes the kernel.
The problem is that ktracing mplayer does not help as filesystem can't keep
ktrace.out being written just before crash. I tried 'sync' mount,
it does not help too.

I decided to divert ktrace.out to /dev/cuaa0 so another FreeBSD will keep it.
However, ktrace() in src/sys/kern/kern_trace.c does not permit writing to
non-regular file. Why?

Eugene Grosbein

P.S. Please CC: me as I'm not in a list.