[PATCH] kconfig: Add support for out-of-tree config fragment and defconfig

[Ryan Eatmon]

On 11/5/2025 9:19 AM, Tom Rini wrote:
> On Wed, Nov 05, 2025 at 09:13:15AM -0600, Ryan Eatmon wrote:
>>
>>
>> On 11/5/2025 8:42 AM, Tom Rini wrote:
>>> On Wed, Nov 05, 2025 at 03:53:16PM +0530, Neha Malcom Francis wrote:
>>>
>>>> Add support for fetching config fragments and defconfigs out-of-tree using
>>>> CONFIG_FRAGMENT_PATH and CONFIG_DEFCONFIG_PATH respectively.
>>>>
>>>> Signed-off-by: Neha Malcom Francis <n-francis at ti.com>
>>>> ---
>>>>    scripts/kconfig/Makefile | 10 +++++++++-
>>>>    1 file changed, 9 insertions(+), 1 deletion(-)
>>>
>>> Isn't this what scripts/kconfig/merge_config.sh is for? No, you can't
>>> just do "make foo_defconfig bar.config" directly, but your tooling that
>>> knows about outside fragments can merge foo_defconfig with
>>> /somewhere/bar.config directly.
>>
>> The problem is the Yocto recipes.  There is a somewhat fixed manner in which
>> the recipe is setup and optionally adding steps is way more invasive than
>> just adding an option to the make command.
> 
> The merge_config.sh tool came from the OpenEmbedded community pushing
> things up to the kernel, so this sounds like a problem to resolve in the
> u-boot recipes/classes, and not something to change here. Feel free to
> loop me in on patches / discussions over on the appropriate list(s)
> there, thanks.

There was a recent patch to the uboot classes in yocto that allow for 
passing extra options to the make command line in for uboot.  This is 
intended not for "primary" platform configs, but for multiple alternate 
testing configs that can be built at the same time as the primary. 
Effectively, the code loops over the multiple configs in different build 
directories and configures/compiles uboot multiple times and then names 
all of the output files uniquely.

That flow has been in Yocto for a very long time and is, again, somewhat 
rigid in what it can allow for changing for each of the variant builds. 
It was designed to build different defconfigs which is what we are 
trying to do here.  But since we do not want to store the defconfigs for 
all of these variants in the uboot source itself, we need to be able to 
tell uboot that the config is in a different location other than in the 
uboot source.  Hence the most straight forward solution was a variable 
on the make to allow for specifying where to look for the out of tree 
defconfigs.

-- 
Ryan Eatmon                reatmon at ti.com
-----------------------------------------
Texas Instruments, Inc.  -  LCPD  -  MGTS