WHAT IS IT
----------
This set of scripts is meant to make it easier to rebuild the kernel
for some Android TV boxes.


SETTING UP
----------
To compile the kernel, you will need the following:

For S905/S912 CPUs you need a fresh snapshot of AMLogic's "OpenLinux"
GIT repository (http://openlinux.amlogic.com). The latest snapshot
as of today can be found here:

    kernel 3.14 (for Android 6):
    http://openlinux.amlogic.com:8000/download/ARM/filesystem/Linux_BSP/buildroot_openlinux_kernel_3.14_wayland_20170630.tar.gz

    kernel 4.9 (for android 7 and 8):
    http://openlinux.amlogic.com:8000/download/ARM/filesystem/Linux_BSP/buildroot_openlinux_kernel_4.9_20180907.tar.gz

Unpack it in same directory where akbuilder resides (you can override it
by specifying AMLOGIC_BUILDROOT_DIR= on make command line).

For X92 box only you will need a copy of the linux_vfd project, which
contains the LCD display driver and controlling daemon for X92, from here:

    https://github.com/anpaza/linux_vfd

Place "linux_vfd" directory in same directory where akbuilder resides
(you can override it by specifying LINUX_VFD_DIR= on make command line).

Also, you have to download the automatic framerate daemon from here:

    https://github.com/anpaza/afrd

Place it alongside the linux_vfd and akbuilder subdirectories.

The final directory structure should look like this:

    [ . ]
    +---[ afrd ]
    +---[ akbuilder ]
    +---[ buildroot_openlinux ]
    +---[ linux_vfd ]

To start building, just run in akbuilder directory:

    make PLATFORM=... bootimg

(where PLATFORM is one of the subdirectories under platforms/).
By default it will build for X92 platform.

If everything goes well, it will build a replacement boot.img for your
platform. Otherwise it will display a message telling what's wrong;
fix the problem and try again.

The final rebuilt boot.img will be placed under out/$(PLATFORM)/.
Note that you CANNOT use it as a replacement for the 'boot' partition
on your device due to a bug in u-Boot startup scripts. This bug will
cause the kernel from boot partition to be launched with an OLD DTB file
used for u-Boot itself (DTB describes the current platform).
The new kernel will simply crash with an old DTB.

Instead, you need to copy the boot.img and the DTB file to a USB stick
(or SD card). Also you have to place a u-Boot script named
aml_autoscript (on S912 devices) or s905_autoscript (on S905 devices)
which is automatically launched by u-Boot at startup, if you press
the 'undocumented' button inside the AV jack. To build the autoscript
you need the u-Boot mkimage tool installed (it is available for most
Linux distributions, the package is named somehow like uboot-tools).

For simplicity, there's an 'bootfiles' target which will prepare everything
for you in directory out/$(PLATFORM)/. Just copy all the files that
'make bootfiles' places there to a USB stick and boot.

Command line examples:

- Build boot.img files for the 2Gb and 3Gb X92 variants:

    make bootimg PLATFORM=X92 BOOTIMG.FILE=boot-2G.img KERNEL.DTS=gxm_x92_2g.dts
    make bootimg PLATFORM=X92 BOOTIMG.FILE=boot-3G.img KERNEL.DTS=gxm_x92_3g.dts

- Try the 4.19 kernel on X92:

    make bootfiles PLATFORM=X92 PLATFORM_KERNEL_VER=4.19

- Build the image for X96 Max box:

    make bootfiles PLATFORM=X96max BOOTIMG.FILE=kernel.img KERNEL.DTS=g12a_x96max_4g.dts


CREDITS
-------

This package contains a copy of carliv_mkbootimg_tools, the original can be found here:

    https://github.com/carliv/carliv_mkbootimg_tools