[QUESTION] Is there a better way to get ftrace dump on guest?

[Namhyung Kim <namhyung@kernel.org>]

Hello,

I'm running some guest machines for kernel development.  For debugging
purpose, I use lots of trace_printk() since it's faster than normal
printk().  When kernel crash happens the trace buffer is printed on
console (I set ftrace_dump_on_oops) but it takes too much time.  I
don't want to reduce the size of ring buffer as I want to collect the
debug info as much as possible.  And I also want to see trace from all
cpu so 'ftrace_dump_on_oop = 2' is not an option.

I know the kexec/kdump (and the crash tool) can dump and analyze the
trace buffer later.  But it's cumbersome to do it everytime and more
importantly, I don't want to spend the memory for the crashkernel.

So what is the best way to handle this?  I'd like to know how others
setup the debugging environment..

Thanks,
Namhyung