On Mon, 2013-02-18 at 17:50 +0100, Vincent Guittot wrote:

yes for sure.
The problem is more linked to cpuidle and function tracer.

cpu hotplug and function tracer work when cpuidle is disable.
cpu hotplug and cpuidle works if i don't enable function tracer.
my platform is dead as soon as I enable function tracer if cpuidle is
enabled. It looks like some notrace are missing in my platform driver
but we haven't completely fix the issue yet

You can bisect to find out exactly what function is the problem:

 cat /debug/tracing/available_filter_functions > t
 
f(t) {
 num=`wc -l t`
 sed -ne "1,${num}p" t > t1
 let num=num+1
 sed -ne "${num},$p" t > t2

 cat t1 > /debug/tracing/set_ftrace_filter
 # note this may take a long time to finish

 echo function > /debug/tracing/current_tracer

 <failed? bisect f(t1), if not bisect f(t2)>
}

-- Steve