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SubjectRe: [PATCH 1/2] function-graph: disable when both x86_32 and optimize for size are configured

On Sat, 20 Jun 2009, Ingo Molnar wrote:

>
> * Steven Rostedt <rostedt@goodmis.org> wrote:
>
> > diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
> > index 4a13e5a..1eac852 100644
> > --- a/kernel/trace/Kconfig
> > +++ b/kernel/trace/Kconfig
> > @@ -121,6 +121,7 @@ config FUNCTION_GRAPH_TRACER
> > bool "Kernel Function Graph Tracer"
> > depends on HAVE_FUNCTION_GRAPH_TRACER
> > depends on FUNCTION_TRACER
> > + depends on !X86_32 || !CC_OPTIMIZE_FOR_SIZE
> > default y
>
> Hm, nice fix, but this is a quite nasty constraint - distros like to
> enable CC_OPTIMIZE_FOR_SIZE as it neatly trims the kernel's size by
> about 30%.
>
> Just in case you have not checked yet: is there no way to turn off
> the specific gcc optimization that causes this? Or is it -Os itself
> that does this optimization?

It seems to me that -Os causes it for i386. I did a make V=1 to capture
how the files in question were being compiled, and tried various disabling
of flags. -Os was the only one to make a difference. :-(

-- Steve



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