[U-Boot] [PATCH v4 0/8] Provide a mechanism to avoid using #ifdef everywhere

[Simon Glass]

Hi Albert,

On Sun, Jun 23, 2013 at 12:29 AM, Albert ARIBAUD
<albert.u.boot at aribaud.net>wrote:

> Hi Simon,
>
> On Mon, 17 Jun 2013 07:44:52 -0700, Simon Glass <sjg at chromium.org>
> wrote:
>
> > Note that a config_drop.h file is added - this defines all the CONFIGs
> > which are not used in any board config file. Without this, autoconf
> cannot
> > define the macros for this CONFIGs.
> >
> > Compile time for main.c does not seem to be any different in my tests.
> The
> > time to perform the 'dep' step (which now creates autoconf.h) increases,
> > from about 2.8s to about 4.6s. This additional time is used to grep, sed
> > and sort the contents of all the header file in U-Boot. The time for an
> > incremental build is not affected.
> >
> > It would be much more efficient to maintain a list of all available
> CONFIG
> > defines, but no such list exists at present.
>
> Stop me if I am wrong, but do you not have this list already, since at
> one point you grep, sed and sort the whole list of config options, then
> at another point generate the list of unused ones?
>

Well yes I create the list. But I don't 'have' it in the sense that it is a
pre-existing file in the tree. My point was that if the file existed I
would not need to create it in the build system. I asked about this at one
point, and the comment was made that putting it in the source tree
'staticly' is risky, since someone might add a new option and it would not
work.

Perhaps when Kconfig is in there things will be different.


>
> Granted, that's the list of config options defined, not necessarily the
> list of options used, but a second variation of the grep/sed/sort might
> give you a hint on that.
>
> Plus, I would love having scripts in tools/ that look for either
> defined or used config options.
>

With this series you kind-of get this feature - you can look at the files
it creates along the way.

Regards,
Simon