[U-Boot] [PATCH v2 4/5] env: Allow environment files to use the C preprocessor

[Simon Glass]

Hi Stephen,

On Wed, Jun 26, 2013 at 2:05 PM, Stephen Warren <swarren at wwwdotorg.org> wrote:
> On 06/24/2013 02:46 PM, Simon Glass wrote:
>> In many cases environment variables need access to the U-Boot CONFIG
>> variables to select different options. Enable this so that the environment
>> scripts can be as useful as the ones currently in the board config files.
>
> The addition of += seems like a separate change to enabling
> pre-processing, but I guess they're both simple enough and this is a new
> features, perhaps it's not a big deal.

Yes it is separate but I was concerned about not creating too many
patches for the same feature.

>
>> diff --git a/Makefile b/Makefile
>
>>  $(obj)include/generated/environment.in: $(obj)include/generated/autoconf.mk.base \
>>               $(wildcard $(ENV_FILE))
>>       if [ -f "$(ENV_FILE)" ]; then \
>> -             cat $(ENV_FILE) >$@ ; \
>> +             $(CPP) -P $(CFLAGS) -x assembler-with-cpp -D__ASSEMBLY__ \
>> +                     -include $(obj)include/config.h $(ENV_FILE) -o $@; \
>
> I guess -undef doesn't make sense here, since config.h could well rely
> on standard pre-defined macros.

In some cases yes.

>
> Does it make sense to -D __UBOOT_CONFIG__ rather than, or in addition
> to, -D __ASSEMBLY__ here, so headers can tell what they're being
> included for? The series I sent for dtc+cpp did -D __DTS__ for similar
> reasons.

Will do.

>
>> diff --git a/tools/scripts/env2string.awk b/tools/scripts/env2string.awk
>
>> +             # Deal with +=
>> +             if (match(var, "(.*)[+]$", var_arr)) {
>> +                     var = var_arr[1]
>> +                     env = vars[var] env
>> +             }
>
> Does this work if you write just:
>
> foo+=bar
>
> rather than:
>
> foo=
> foo+=bar
>
> It might be worth allowing the former syntax, so you don't need to
> explicitly assign empty values before a sequence of ifdef'd +=
> operations. If the above blows up, at least a descriptive error message
> might be useful.

Yes that works for me. With awk variable appear when used which helps here.

Regards,
Simon