[Lucid][SRU] fsl-imx51: Enabling function tracer and function profiler of the ftrace

[Chase Douglas]

On Wed, May 5, 2010 at 10:18 PM, AceLan Kao <acelan.kao at canonical.com> wrote:
> The fsl-imx51 branch doesn't support too much features of the ftrace,
> including FUNCTION_GRAPH_TRACER, DYNAMIC_FTRACE, MMIOTRACE
> Do you think is there any other useful options should be enabled?
> I can try to see if they're supported in the fsl-imx51 branch.

if DYNAMIC_FTRACE is not supported, then we don't want any of this
enabled by default. DYNAMIC_FTRACE is the magic that lets you turn
tracing on and off at runtime. If you can't do that, then everything
will be traced all the time. This would hurt performance.

It looks like this could be resolved soon for ARM though:
http://thread.gmane.org/gmane.linux.kernel/949812, but I haven't read
all the replies, and it hasn't landed in Linus' tree nor in Steve
Rostedt's.

Thus, NACK from me for enabling ftrace on any ARM platform until it
has DYNAMIC_FTRACE support. Of course, we can still make debug kernels
for specific testing, we just can't enable it for a release kernel.

-- Chase