How to make a buildroot rootfs for MIPS CI20

To make a buildroot rootfs tarball run

git clone git://git.busybox.net/buildroot buildroot cd buildroot make qemu_mipsel_malta_defconfig make menuconfig

The malta_defconfig is a good basic start and boots on the ci20.

Enable the following options in buildroot

Toolchain --> Toolchain type --> External toolchain (download or select path of your preinstalled toolchain) Filesystem images --> cpio the root filesystem tar the root filesystem Kernel --> 

Exit and Save the configuration.

make

Once the build has finished (can take quite some time. You are making an OS) you should have the following outputs output/images/rootfs.cpio.gz output/images/rootfs.tar

file.

That is basically it.

When you followed the steps on http://elinux.org/CI20_Dev_Zone#Making_a_bootable_SD_card_from_sources

Mount the ext4 partition on your sd card using

sudo mount /dev/sdx1 /mnt

where sdx is your sd card writer (find using lsblk).

Extract the rootfs.tar using

sudo tar -xvf output/images/rootfs.tar /mnt/

At the u-boot prompt, you might want to check your bootargs being passed to the kernel.

printenv

They should be something like this bootargs=console=ttyS4,115200 console=tty0 mem=256M@0x0 mem=768M@0x30000000 clock_ignore_unused

You need to add the following to your bootargs root=/dev/mmcblk0p1 rootwait devtmpfs.mount=1

This can be done via

setenv bootargs console=ttyS4,115200 console=tty0 mem=256M@0x0 mem=768M@0x30000000 clock_ignore_unused root=/dev/mmcblk0p1 rootwait devtmpfs.mount=1

Note: Do check your serial console. You might be using ttyS0 instead of ttyS4

If you want to save the environment for uboot to run every time.

saveenv

run

boot

And enjoy :).

You can extend the basic configuration of buildroot now. Simply go to the root folder where you cloned the buildroot repository.

make menuconfig

Select any that you want for target packages. Look closely enough and you will find an X window manager too :) Save and exit the menuconfig.

Run make again. And extract the rootfs onto your sd card ext4 partition again.