[Buildroot] initramfs doesn't get linked into kernel

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

Dear Adam Nielsen,

On Sat, 27 Apr 2013 09:37:59 +1000, Adam Nielsen wrote:

> I'm trying to figure out how to get the initramfs image linked in to my kernel 
> zImage.  I have selected BR2_TARGET_ROOTFS_INITRAMFS (the only option I can 
> find in the menuconfig containing 'initramfs') but nothing gets linked in to 
> my kernel.
> 
> I am using a custom kernel config, and I tried putting the filename of the 
> buildroot-generated .cpio image in as CONFIG_INITRAMFS_SOURCE which linked in 
> successfully, but then it won't boot as it appears you are supposed to put an 
> initramfs configuration filename here instead.
> 
> Is it correct that I have to manually put something into 
> CONFIG_INITRAMFS_SOURCE?  If so, what should I place here to use the rootfs 
> generated by buildroot?

If you let Buildroot build your kernel, it does that automatically (see
the code in linux/linux.mk). If you build your kernel outside of
Buildroot, you have to set CONFIG_INITRAMFS_SOURCE correctly.

If you build your kernel outside of Buildroot, pointing
CONFIG_INITRAMFS_SOURCE to the .cpio image works just fine. I'm doing
that all the time here. Here's what I have in my kernel configuration:

CONFIG_INITRAMFS_SOURCE="../marvell-rootfs/images/rootfs.cpio"

Could you attach your Buildroot .config, and your kernel configuration
file (output/build/linux-x.y.z/.config if you build your kernel with
Buildroot) ?

Thanks,

Thomas
-- 
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com