Re: [RFC PATCH 3/4] ftrace: Do not test frame pointers if -mfentry is used

From: Linus Torvalds
Date: Wed Aug 08 2012 - 23:46:04 EST


On Wed, Aug 8, 2012 at 3:49 PM, Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:
>
> No, CONFIG_HAVE_FENTRY just means fentry is supported, it does not mean
> that it is being used. It only gets used if CC_USING_FENTRY is set,
> which is set by the Makefile at time of compile.

Btw, it might be lovely to consider the concept of "Kconfig variables
set by shell-scripts".

We currently have a metric sh*t-ton of Makefile magic for testing
various things like this, and integrating it into Kconfig might be a
good idea. That way you would be able to use the Kconfig logic on
these things.

Kconfig already has the "option env=XYZ" syntax for importing values
from the environment variables. Extending it to some kind of "option
shell=xyz" would allow for more complex interactions like this
(imagine testing compiler options and version dependencies in the
Kconfig files instead of the Makefiles)?
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