Re: [PATCH] irqtrace-option-off-compile-fix

From: Tim Chen
Date: Tue Jul 11 2006 - 16:28:35 EST


On Tue, 2006-07-11 at 21:45 +0200, Ingo Molnar wrote:
> * Tim Chen <tim.c.chen@xxxxxxxxxxxxxxx> wrote:
>
> > > The one you want is CONFIG_TRACE_IRQFLAGS .. which is the one that
> > > actually turns the tracing on
> >
> > I could not turn off CONFIG_TRACE_IRQFLAGS_SUPPORT in .config
> > directly. The command "scripts/kconfig/conf -s arch/x86_64/Kconfig" in
> > Makefile overwrites changes made to CONFIG_TRACE_IRQFLAGS_SUPPORT in
> > .config file. So this is always turned on in .config if the option
> > TRACE_IRQFLAGS_SUPPORT is set in arch/x86_64/Kconfig.debug. I may be
> > missing something. Any suggestions?
>
> correct, that flag is always set - it signals towards the core kernel
> that the architecture in question (x86_64) that it has trace-irqflags
> support. NOTE: this does not mean that irqflags tracing is turned on -
> that is another option: CONFIG_TRACE_IRQFLAGS.
>
> unsetting the support flag makes no sense and will likely break the
> build. There is no overhead from irqflags tracing if it's turned off.
> (even if the CONFIG_TRACE_IRQFLAGS_SUPPORT option is set)
>
> does this explain things? We could rename the boolean value to
> CONFIG_TRACE_IRQFLAGS_SUPPORT_AVAILABLE perhaps, to avoid future
> confusion.
>
> Ingo

Thanks for clarifying.

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