This README file contains information on building the meta-rockchip
BSP layer, and booting images.
Please see the corresponding sections below for details.


Dependencies
============

This layer depends on:

  {
  	URI: git://git.openembedded.org/bitbake
	branch: master

  	AND

  	URI: git://git.openembedded.org/openembedded-core
  	layers: meta
	branch: master
	  at least 039211f0d8fe79d07b65f2f02e299b9656034214
	  from Sep 4, 2015
  }

  OR

  URI: git://git.yoctoproject.org/poky
  branch: master
  Tag: 1.9_M2


Contributing
============

Please submit any patches against this BSP to the Yocto Project mailing list:
yocto@yoctoproject.org and cc: the following maintainers:

Maintainer: Romain Perier <romain.perier@gmail.com>
Maintainer: Trevor Woerner <twoerner@gmail.com>

When sending patches please take a look at the contribution guide available
here: https://wiki.yoctoproject.org/wiki/Contribution_Guidelines

Please also send your patches by using git send-email and prefix your subject
by "[meta-rockchip]".

Table of Contents
=================

  I. Configure yocto/oe environment
 II. Building a second level bootloader based on kexec
III. Booting your device
 IV. Performance

I. Configure yocto/oe environment
========================================

In order to build an image with BSP support for a given release, you
need to download the corresponding tools described in the "Dependencies"
section. Be sure that everything is in the same directory.

~ $ mkdir yocto; cd yocto
~/yocto $ git clone git://git.yoctoproject.org/poky -b fido
~/yocto $ git clone git://git.yoctoproject.org/meta-rockchip

Then you need to source the configuration script:
~/yocto $ source poky/oe-init-build-env

Having done that, you can build a
image for a rockchip board by adding the location of the meta-rockchip
layer to bblayers.conf, along with any other layers needed (to access
common metadata shared between BSPs) e.g.:

  /path/to/yocto/poky/meta     \
  /path/to/yocto/meta-rockchip \

To enable the build for a specific board, add its name in the MACHINE variable to local.conf:

  MACHINE ?= "radxarock"

All supported machines can be found in meta-rockchip/conf/machine.

You should then be able to build a image as such:

  $ bitbake core-image-minimal

At the end of a successful build, you should have an image in
/path/to/yocto/build/tmp/deploy/<MACHINE>/<IMAGE_NAME>. See Yocto
manual for more details.

II. Building a second level bootloader based on kexec
=====================================================

This BSP contains "Petitboot", a kexec-based second leval bootloader.
As all available bootloaders provided by Rockchip are very limited and do not allow
to boot from a block device containing a file system or from the network, we decided
to use Petitboot, which just needs a minimalistic kernel to work.

See https://www.kernel.org/pub/linux/kernel/people/geoff/petitboot/petitboot.html

In a terminal, just type the following command:
~/yocto $ bitbake linux-petitboot

At the end of a successful build, you should have an image
/path/to/yocto/build/tmp/deploy/<MACHINE>/RK3XPetitbootLoader-<MACHINE>.bin.
This image is already to the right format, so you can directly flash it as a
kernel image to a Rockchip device with upgrade_tool.

III. Booting your device
========================

Petitboot allows you to boot a kernel from the EMMC, an SDCARD, an USB storage
device or even tthe network (it just needs to be supported by the Linux kernel).
In order to do so, you need to put a configuration file at the root of the target
device. Petitboot supports differents kind of configuration files, in this example
we will an SDCARD and a kboot configuration file.

Copy your kernel image and your dtb under the /boot directory, on your device.
Then create a kboot.conf in / and add the following content:

linux-next from sdcard='/boot/zImage dtb=/boot/<MACHINE>.dtb root=/dev/mmcblk0p2 rootwait console=ttyS2,115200 earlyprintk'
linux-next from tftp='tftp://192.168.0.5/zImage dtb=tftp://192.168.0.5/<MACHINE>.dtb root=/dev/mmcblk0p2 rootwait console=ttyS2,115200 earlyprintk'
# You can also use nfs
# nfs='nfs://192.168.0.5/fire/boot/vmlinux.strip root=/dev/nfs rw ip=dhcp video=1080p fbcon=rotate:3'
# Or http and nfs mixed together
# http_nfs='http://192.168.0.5/ice/boot/vmlinux.strip nfs://192.168.0.5/ice/boot/initrd root=/dev/nfs'

Then, plug your SDCARD into your Rockchip device and power on the board. If
everything worked fine, Petitboot should be started automatically and list all 
entries found in the configuration file.

IV. Performance
===============

By default a BSP layer should not be tuning a build, this is a DISTRO-level
decision. As such the default machine settings are meant to be the lowest
common denominator in order to maximize generality. If you are interested in
tweaking your build to maximize performance you can either use a DISTRO that
has these same goals, or you can add settings in your configuration files
(e.g. local.conf) as follows:

	for rk3288:
		DEFAULTTUNE = "cortexa17hf-neon-vfpv4"
	for rk3066:
		DEFAULTTUNE = "cortexa9-neon"