[Buildroot] First rootfile system build using buildroot

[Thomas Petazzoni <thomas.petazzoni@free-electrons.com>]

Dear Dinesh Guleria,

On Tue, 1 Sep 2015 06:39:34 +0530, Dinesh Guleria wrote:

> One more question from my side if i use " Sourcery
> CodeBench 2014.05"  toolchain then buildroot will download it for me or i
> have to download it manually ?

Buildroot will download it for you.

> Also if buildroot will download it then in
> this case will it be a one time process or if i make a new build for my
> rootfile system, then every time tool chain will be downloaded ?

It is a one time process. Buildroot keeps a cache of the downloaded
files into the dl/ sub-directory (which can be customized using the
BR2_DL_DIR configuration option, which is also an environment variable).

> What exactly the diffrence between using external tool chain like Sourcery
> CodeBench 2014.05"  & building toolchain using crosstool-ng ?
> http://www.bootc.net/archives/2012/05/26/how-to-build-a-cross-compiler-for-your-raspberry-pi/

Sourcery CodeBench 2014.05 is a pre-built toolchain, used by a lot of
people. It's already there and available, hopefully quite well tested.
However, since it's pre-built, you cannot customize it.

Using crosstool-ng to build your toolchain allows to generate a
completely custom toolchain, tailored for your platform.

> >> Building the rootfilesystem into zImage resolves the rootfilesystem
> loading/linking issue clearly.
> 
> Will uboot be able to understand that my rootfilesystem is inside my zimage
> ? Or i have to tell uboot explicitly ?

If you're using an initramfs bundled inside the zImage, then U-Boot
does not even need to know about it. Just load the zImage in U-Boot,
start the kernel, and that's it.

Best regards,

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