On Fri, 19 Jun 2015 14:17:03 +0200
Torsten Duwe [off-list ref] wrote:

On Fri, Jun 19, 2015 at 10:15:44AM +0300, Denis Kirjanov wrote:

quoted

Hi Torsten,

could you provide a description how you did test that.

Vanilla kernel, those patches on top, built as described to
Steven in the previous mail (.config attached there, built
natively on ppc64le ABIv2, mentioned tool versions)

Great that you got it working on your machine. But you need to do it in
a way that you don't break builds of existing machines, with existing
(still supported) compilers.

-- Steve

make vmlinux, make modules, build initrd
qemu-system-ppc64 -no-reboot -enable-kvm -m 20480 -kernel vmlinux
  -initrd initrd.gz -append console=hvc0 -nographic -vga none
inside:
cd /sys/kernel/debug/tracing
mkdir instances/Foo
cd instances/Foo
echo function > current_tracer

current_tracer holds "nop" or "function"; the transition is accompanied 
by heavy binary patching. When the function tracer is active, almost all
calls go through ftrace_caller. This should be enough for a start; the
proper stack frame layout details for the tracer functions still remain
to be checked...

	Torsten