[Buildroot] buildroot configuration files -- query

[Thomas Petazzoni]

Dear Dinesh Guleria,

On Wed, 4 Nov 2015 16:06:49 +0530, Dinesh Guleria wrote:

> I am referring following document to learn buildroot.
> http://buildroot.uclibc.org/downloads/manual/manual.html
> 
> 1> What exactly is the difference between the configuration files in*
> /board* directory & */configs* directory ?
> 
>    For example these two config files are for at91sam9260ek MCU :--
>    /board/atmel/at91sam9260ek/linux-3.9.config

This is a Linux kernel configuration file. It describes which kernel
features are enabled (drivers, filesystems, network protocols, kernel
features, etc.).

>    /configs/at91sam9260eknf_defconfig

This is a Buildroot configuration file. It describes your embedded
Linux system as a whole (architecture, toolchain, target packages,
etc.).

> 2> we can load the configuration using following command :--
>   * make <name>_defconfig command*
> 
>    we can save a configuration by following command *make savedefconfig*.
> As said in following section :--
>    9.3. Storing the Buildroot configuration
>    The Buildroot configuration can be stored using the command make
> savedefconfig.
>    The recommended place to store this defconfig is
> configs/<boardname>_defconfig.
> 
>    a> Now my question how the configuration file for new MCU is created
> first time in /configs directory. What is the command to use for this ?

"make savedefconfig", which by default will create a file named
"defconfig", which you simply move to configs/, under a name like
<blabla>_defconfig:

$ make savedefconfig
$ mv defconfig configs/blabla_defconfig

>    b> How the configuration file for a particular board is created first
> time & saved (lets say for example this /board/atmel/XXXX)
>       Now how to create & save configuration file for XXXX board ? What is
> command to use for this ?

It's not a configuration file for a "board", but for example a Linux
kernel configuration file. If you're talking about the Linux kernel
configuration file, then you can use the "make linux-update-config" or
"make linux-update-defconfig" targets.

See the manual for more details, or also
http://free-electrons.com/doc/training/buildroot/buildroot-slides.pdf
slide 74 and following.

Best regards,

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com