[U-Boot] [PATCH] Clean all defconfigs with savedefconfig

[Stephen Warren]

On 05/11/2015 02:17 PM, Joe Hershberger wrote:
> Hi Stephen,
>
> On Mon, May 11, 2015 at 3:02 PM, Stephen Warren <swarren at wwwdotorg.org> wrote:
>> On 05/11/2015 11:08 AM, Joe Hershberger wrote:
>>>
>>> In order to reduce merge conflicts and to maintain the simplest possible
>>> defconfig files, we should be using the savedefconfig feature of Kconfig
>>> every time a new feature is added. This keeps the defconfig settings to
>>> a minimum (only those things not default) and keeps them in the same
>>> order as the Kconfig options.
>>
>>
>>> diff --git a/configs/jetson-tk1_defconfig b/configs/jetson-tk1_defconfig
>>
>>
>>> -CONFIG_TARGET_JETSON_TK1=y
>>
>>
>> Doesn't that (and the equivalent change in other files such as
>> harmony_defconfig) break the build, since the Kconfig option that selects
>> the particular board is no longer selected?
>
> That's a bit of a peculiar case caused by the fact that Kconfig sees
> that board as the default board, so it removes the explicit setting.
>
> The only problem I see with that is if a new board is added to the top
> of the list. We can maybe fix this by changing all of the menus of
> boards to optional, but I'm not sure that's what we want either.

I certainly think we want to make the defconfig files not change 
semantics if someone adds a new board earlier in the list, or otherwise 
changes the sort order.

Right now, the defconfig files do this by explicitly containing an entry 
for the board to build for, even if it's the default in Kconfig. that's 
at least simple, but interacts badly with savedefconfig.

Perhaps we can modify e.g. arch/arm/mach-tegra/tegra124/Kconfig (and all 
other Kconfig files with choices like this, i.e. choices that are more 
than simply a different value that's selected but rather change the 
whole meaning of the build target) to explicitly set the default. That 
way, if the order of choice entries changes, the defconfig won't change 
meaning. For example:

choice
         prompt "Tegra124 board select"
         # Do not change this value without editing the defconfig for the
         # board that the current default. You'd need to add e.g.:
         # CONFIG_TARGET_JETSON_TK1=y to that file.
	default TARGET_JETSON_TK1