Pascal Van Leeuwen <pvanleeuwen@xxxxxxxxxxxxxxxx> a écrit :
> Quick question regarding how to configure out code depending on a
CONFIG_xxx
> switch. As far as I understood so far, the proper way to do this is
not by
> doing an #ifdef but by using a regular if with IS_ENABLED like so:
>
> if (IS_ENABLED(CONFIG_PCI)) {
> }
>
> Such that the compiler can still check the code even if the switch is
> disabled. Now that all works fine and dandy for statements within a
> function, but how do you configure out, say, global variable
definitions
> referencing types that are tied to this configuration switch? Or
should
> I just leave them in, depending on the compiler to optimize them away?
>
> Obviously the code depends on those variables again, so if it's not
> done consistently the compiler will complain somehow if the switch is
not
> defined ...
>
> Also, with if (IS_ENABLED()) I cannot remove my function prototypes,
> just the function body. Is that really how it's supposed to be done?
>
Yes. Code and data with static linkage will just be optimized away by
the compiler if the CONFIG_xx option is not enabled, so all you need
to guard are the actual statements, function calls etc.
Ok, makes sense. Then I'll just config out the relevant function bodies
and assume the compiler will do the rest ...
No need to config out function bodies when they are static.
If not, it's better to group then in a C file and associate that file
to the config symbol through Makefile
Christophe
Thanks,
Pascal van Leeuwen
Silicon IP Architect, Multi-Protocol Engines @ Inside Secure
www.insidesecure.com
