[Buildroot] make savedefconfig

[Dallas Clement]

Thanks Samuel.  This helps tons.  Will see how far I get with this new
found knowledge!

On Fri, Sep 14, 2012 at 6:52 PM, Samuel Martin <s.martin49 at gmail.com> wrote:
> Hi Dallas,
>
> 2012/9/15 Dallas Clement <dallas.a.clement at gmail.com>:
>> Greetings,
>>
>> I'm not feeling overly confident in 'make savedefconfig'.  It appears
>> to not save everything I think it should after making changes with
>> 'make menuconfig'.  I have attached a comparison of my original config
>> file (shown on the right) with the defconfig file produced by 'make
>> savedefconfig' (shown on the left).  As you can see, the items shown
>> in red did not make it into the defconfig.  Some of these are pretty
>> important, such as:
>>
>> BR2_BUSYBOX_VERSION
>> BR2_ROOTFS_SKELETON_CUSTOM_PATH
>> BR2_LINUX_KERNEL_UBOOT_IMAGE
>> BR2_LINUX_KERNEL_UIMAGE
>>
>> The other thing I noticed is that if I do a 'make
>> blah-blah-defconfig', and then look at the .config file, most of the
>> settings from the defconfig show up in the .config, with a few
>> exceptions:
>>
>> BR2_ROOTFS_SKELETON_CUSTOM_PATH
>> BR2_BUSYBOX_VERSION
>>
>> These are reverted from my changes to the default values.
>>
>> I'm using buildroot 2012.08.
>>
>> Would appreciate if anyone could confirm whether this is buggy
>> behavior or I am just doing something wrong.
>>
> AFAIK, 'savedefconfig' only stores all symbols that differ from the
> default ones (which are defined in the Config.in files).
> Thus, kconfig is able to regenerate the whole configuration:
> - either using the .config file (which stores all symbols);
> - or, combining the defconfig + the defaults from the Config.in files.
>
> A defconfig is just the minimal set of symbols you need to record in
> order to retrieve your configuration on the next run.
>
>
> Cheers,
>
> --
> Sam