[U-Boot] [PATCH V3] Makefile: remove BUILD_TAG from KBUILD_CFLAGS

[Simon Glass]

On 11 February 2016 at 00:59, Masahiro Yamada
<yamada.masahiro at socionext.com> wrote:
> 2016-02-11 7:16 GMT+09:00 Stephen Warren <swarren at wwwdotorg.org>:
>> From: Stephen Warren <swarren at nvidia.com>
>>
>> If BUILD_TAG is part of KBUILD_CFLAGS, then any time the value changes,
>> all files get rebuilt. In a continuous integration environment, the value
>> will change every build. This wastes time, assuming that incremental
>> builds would otherwise occur.
>>
>> To solve this, remove BUILD_TAG from KBUILD_CFLAGS and add it to CFLAGS
>> for just the one file that uses it. This does have the disadvantage that
>> if any other files want to use the flag, we'll need to duplicate this
>> custom CFLAGS setup logic. However, it seems unlikely we'll need this.
>>
>> An alternative would be to add BUILD_TAG to the "local version" and remove
>> the special case code from display_options.c. However, that would affect
>> the format of the U-Boot signon message, which may negatively affect
>> people looking for specific data there. The approach of using
>> file-specific CFLAGS was suggested by Masahiro Yamada.
>>
>> Signed-off-by: Stephen Warren <swarren at nvidia.com>
>> ---
>> v3: Undo accidental removal of bch.o.
>> v2: Set CFLAGS on display_options.c rather than modifying
>> scripts/setlocalversion to add BUILD_TAG to the local version.
>
>
> Reviewed-by: Masahiro Yamada <yamada.masahiro at socionext.com>

Acked-by: Simon Glass <sjg at chromium.org>