Re: [PATCH 00/15] [git pull] for tip/tracing/ftrace

[Ingo Molnar <mingo@elte.hu>]

* Sam Ravnborg <sam@ravnborg.org> wrote:

> On Tue, Feb 17, 2009 at 07:49:49AM -0500, Steven Rostedt wrote:
> > 
> > On Tue, 17 Feb 2009, Ingo Molnar wrote:
> > 
> > > 
> > > * Steven Rostedt <rostedt@goodmis.org> wrote:
> > > 
> > > > Ingo,
> > > > 
> > > > This is a patch series that offers a variety of features.
> > > > 
> > > > The first is to add:
> > > > 
> > > >  #### all functions enabled ####
> > > > 
> > > > to set_ftrace_filter when all functions will be traced when function
> > > > tracing is on.
> > > > 
> > > > The next is to add a :command: interface, and the module command:
> > > > 
> > > >  echo '*:mod:ext4' > set_ftrace_filter
> > > > 
> > > > Will select all functions in the ext4 module.
> > > > 
> > > >  echo '!*write*:mod:ext4' > set_ftrace_filter
> > > > 
> > > > will remove all functions with the characters 'write' and are
> > > > in ext4.
> > > 
> > > Very nice feature!
> > > 
> > > I'm wondering, would it be possible to somehow extend this to 
> > > built-in drivers too, so that we get symmetry of usage 
> > > independently of whether something is built in or a module? I 
> > > suspect it needs some extensions to kbuild though ...
> > 
> > Yeah, that may needs some kbuild magic.
> 
> I have not followed this thread.
> What kind of magic do you have in mind?

It would be nice to have a notion of 'modules' even for built-in 
drivers - at least as far as symbol lookups go.

It would allow such a module-specific trigger:

    echo '!*write*:mod:ext4' > set_ftrace_filter

to work even if ext4 is built-in.

	Ingo