Cubox-i

This document [[Article description::describes how to install Gentoo on the SolidRun Cubox-i and HummingBoard.]]

Prerequisites
Mandatory


 * Cubox-i
 * CuBox-i2ex, CuBox-i2Ultra or CuBox-i4Pro if the serial console is used. Otherwise a HDMI display and a USB keyboard.
 * 4 GB+ SD card.
 * Network cable during installation. WiFi can be enabled later.
 * Gentoo system with a cross-compiler for ARM installed.

Optional


 * TFTP server.
 * SolidRun Ignition image to test if the Cubox-i device is working with the serial console, or the connected display and keyboard. This will overwrite the U-Boot installation!
 * SolidRun Ignition image to test if the Cubox-i device is working with the serial console, or the connected display and keyboard. This will overwrite the U-Boot installation!

Installation
The install consists of installing, partitioning and formatting, the SD card. Copying over a stage3 tarball, configuring it so that it can boot and it can be accessed. Creating a kernel. Booting the kernel on the machine. Installing the kernel for an automatic boot. Continue a default Gentoo installation.

Cross-compiler
crossdev is required to build U-Boot and the kernel on an or  system.

Install crossdev:

Build a cross-compilation toolchain:

For more information, please refer to the Creating a cross-compiler (Embedded Handbook) and Crossdev articles.

Mainline
When the Cubox-i was released it had no mainline U-Boot support. Instead SolidRun maintained its own patched fork. Since v2017.01 mainline U-Boot works without any patches, so there is no longer a reason to use the SolidRun fork.

Setup the cross-compilation environment:

Clone the U-Boot Git repository:

Mainline U-Boot has no support, although it does have  support which is just as easy if not easier to use. If support is still desired, apply the patch by.

Build U-Boot:

A successful build will create two files in the source tree directory, and


 * is the actual machine detection and initialization and must be flashed at offset 1 KByte of the boot SD card.
 * is the second stage bootloader; it can be flashed at offset 69 KByte of the boot SD card;

SolidRun
SolidRun provides a fork of mainline U-Boot with board support package (BSP) vendor branches. For more information, please refer to the SolidRun Knowledge Base.

Setup the cross-compilation environment:

Clone the U-Boot Git repository:

Build U-Boot:

A successful build will create two files in the source tree directory, and


 * is the actual machine detection and initialization and must be written at offset 1 KByte of the boot SD card.
 * is the second stage bootloader; it can be written at offset 69 KByte of the boot SD card; alternatively it can be placed as-is on the first partition of the SD card if the partition has a FAT filesystem.

Serial console
The Cubox-i2ex, CuBox-i2Ultra and CubBox-i4Pro have serial console support via a FTDI FT230X USB to UART serial interface. This allows connecting the Cubox-i directly to another computer. Alternatively the Cubox-i can be connected to a HDMI display and USB keyboard.

The computer connecting to the Cubox-i will need to have the following kernel configuration options enabled:

Connecting to the serial console requires an application such as or. For more information, please refer to the SolidRun Knowledge Base.

Creating the partitions
A single partition scheme can be used with mainline U-Boot when using an ext2/3/4 formatted root partition. However when using a Btrfs formatted root partition (or other unsupported filesystem), an ext2/3/4 or FAT32 formatted boot partition is required.

Creating filesystems
Create the filesystems on the boot and root partitions:

Mounting the partitions
Mount the boot and root partitions:

Unpacking the stage tarball
Go to the mount point where the root filesystem is mounted:

Get the latest stage 3 and extract it to the root partition:

Creating the fstab file
Add the following entries to the fstab file:

Setting a default root password
To be able to login after booting, set a default password by creating a password hash and adding it to the shadow file:

In this example the password hash corresponds to the password "cubox".

The default shadow entry for the user will look like:

Replace the  with the password hash from the  command above:

Enabling the serial console
To have a serial console available after booting, change the  line to the following:

Kernel
The mainline kernel 3.19+ and has great support for Cubox-i devices, complete with working graphics and networking.

Create the install directories:

Setup the cross-compilation environment:

Configure the kernel:

Build and install the kernel (zImage):

The kernel is located at. The kernel will be installed at

Build and install the kernel modules:

The kernel modules will be installed at

Build and install the device trees:

The device trees are located at. The device trees will be installed at

The kernel, modules and devices trees can now be installed to the actual root directory of the device:

Headers
To compile certain applications like Kodi that have modified/additional codecs you need to expose the patched kernel headers. Fortunately there is a script for that:

If you install them into then you don't overwrite the ones provided by the Gentoo package.

Video Processing Unit
The i.MX6 SoC contains a Video Processing Unit (VPU) that allows video decoding and encoding to be done in hardware. The VPU is supported by the mainline kernel but requires firmware to operate. The following table lists the VPU firmware required by each Cubox-i device.

Instructions for obtaining the VPU firmware can be found at the coda-bits GitHub repository. The firmware needs to be placed in the directory.

WiFi
The following kernel configuration options are required for WiFi support. These options should already be enabled if the kernel was configured with.

The WiFi driver requires firmware to operate, which can be obtained directly from the Linux firmware repository or the package. The required firmware can be determined by examining the output of a running Cubox-i device:

The above output from a Cubox-i4Pro indicates that is the firmware required by the driver. This may be differ depending on the Cubox-i model.

The firmware also requires NVRAM calibration data, which can be obtained from the Freescale (now NXP) repository. The NVRAM calibration data needs to have the correct WiFi regulatory domain set. This can be done by setting the value of the  parameter to the country code in which the device will be operating in. For example, to set the WiFi regulatory domain for the United States:

The firmware and NVRAM calibration data need to be placed in the directory.

Bootloader
U-Boot will normally wait three seconds for user input before attempting to boot. If user input is received, the boot sequence is interrupted and an interactive shell is started. If three seconds pass with no user input, U-Boot will look for an environment configuration on the first partition. If no valid environment configuration is found, U-Boot will display *** Warning - bad CRC, using default environment, and will then continue with the default environment configuration. This is where mainline U-Boot and SolidRun U-Boot differ. Mainline supports and extlinux.conf on the first partition, while SolidRun also supports.

extlinux.conf
U-Boot supports Syslinux style boot configuration. U-Boot only borrows a small subset of the Syslinux configuration options, and does not require Syslinux itself. This is much simpler than using or applying patches to add  support.

Create the directory:

Create the following configuration and adjust accordingly:

uEnv.txt
If the patch was applied when building U-Boot, create  in the boot partition or directory:

Adjust the video argument to match the display.

uEnv.txt
If you use the SolidRun U-Boot from this wiki you can use the default settings and no direct modification of the U-Boot configuration might be necessary. If the first partition of the SD card is formatted with ext2 or fat it will read the the file with the configuration from it.

These two lines should be enough to boot the kernel. The U-Boot from this wiki can boot a zImage directly (no conversion to uImage necessary). The zImage and the *.dtb file have to reside in the root folder of this partition next to the. The second line contains the kernel flags (for example the root).

If you have no console output on your screen during boot, try

Interactive
Connect to your Cubox-i with a serial console (or with a keyboard and a display) and interrupt the U-Boot bootloader with and type the following commands.

setenv ipaddr 192.168.0. setenv serverip 192.168.0. setenv bootargs root=/dev/mmcblk0p2 rootfstype=ext4 ro rootwait console=ttymxc0,115200 tftpboot 0x10800000 uimage bootm 0x10800000

This should boot you in your Cubox-i installation and you should be able to login as root with your password. From here you can continue with a default Gentoo installation. To make this boot configuration permanent follow the next step "Default".

Environment
In the following we will make the settings permanent. The uImage file is copied to the boot partition. The first line contains the settings for loading the kernel into memory. The second holds the arguments for the kernel. The third one is the code to execute the kernel.

The bootcmd is called by default and executes theses three steps in order. The last line makes these variables permanent in the U-Boot settings.

setenv mybootload ext2load mmc 0:1 0x10800000 /uimage setenv mybootset setenv bootargs root=/dev/mmcblk0p2 rootfstype=ext4 ro rootwait console=ttymxc0,115200 setenv mybootstart bootm 0x10800000 setenv bootcmd run mybootset mybootload mybootstart saveenv

uEnv
U-Boot can also read configuration values from a file. This way the boot process can be modified without going into the U-Boot console and the settings are permanent as well. The following script is modified from the original mini-image used for the installation.

setenv gsetmmc 'root="root=/dev/mmcblk${rootunit}p$rootpart rootfstype=$rootfs ro rootwait"' setenv gconsole console=ttymxc0,115200 consoleblank=0 setenv gbootextra init=/init setenv grootflags "" setenv gvideo mxcfb0:dev=hdmi,1920x1080M@60,if=RGB24 dmfc=3 setenv gbootpreset 'bootdev=mmc; bootunit=0; bootpart=1; bootfs=ext2; envfile=uEnv.txt; bootroot=; bootfile=uImage' setenv grootpreset 'rootunit=0; rootpart=2; rootfs=ext4' setenv gsetenvscript setenv gbootenv "\'run gset\${bootdev}; setenv bootargs \$root \$gvideo \$gconsole \$gbootextra \$grootflags $end\'" setenv gloaduenv 'if ${bootfs}load $bootdev $bootunit:$bootpart $loadaddr $envfile; then env import -t $loadaddr $filesize; fi' setenv grootpresetup 'bootrun=bootm; loadfile=$bootfile; rootdev=$bootdev; rootunit=$bootunit; rootpart=$rootpart; rootfs=$rootfs' setenv gbootload '${bootfs}load $bootdev $bootunit:$bootpart $loadaddr $bootroot/$loadfile' setenv gbootstart '$bootrun' setenv bootcmd run gbootpreset grootpreset gsetenvscript gloaduenv grootpresetup gbootenv gbootload gbootstart

In the minimal uEnv.txt is enough to boot a stock ext4 system on the SD card. To boot from USB you must use  or.

Continue Gentoo install
Steps that should be done right after the installation:


 * 1) setup network
 * 2) set date
 * 3) emerge-webrsync
 * 4) emerge ntpd
 * 5) /etc/init.d/sshd

Gentoo ARM Handbook (currently unavaliable)

Graphics drivers (FOSS)
Although it's not fully integrated yet, there is useful 2D/3D functionality in the latest FOSS drivers, some of which were only recently added to the Gentoo ARM overlay.


 * mesa - the latest releases enable vivante/imx (be sure and enable gallium/glx/dri3 in mesa)
 * libdrm - enables "experimental" vivante/etnaviv api
 * xf86-video-armada - builds multiple drivers, depends on various versions of dependencies below
 * libdrm-armada - gpu shim
 * libetnaviv (latest is header-only, older is a library)
 * galcore-headers - public "etnaviv" interface

Note: the packages in the main portage tree call the imx VIDEO_CARD "vivante" but in the above Xorg drivers vivante refers to the legacy GAL drivers which are disabled (the FOSS pieces should probably all be called etnaviv). To try the FOSS graphics stack, you should set  in your  file and add the ARM overlay.

So far the imx/armada drivers seem to work for 2D in X but the log shows an error initializing the etnadrm_gpu driver and claims to fall back to swrast 3D. Still, with dri3 and vivante enabled glxgears gets over 110 fps in Xorg, so there is that... (if you only have dri2 enabled then it really is swrast @ 22 fps)

Graphics / Video driver (firmware)
The hardware units have support for decoding certain codecs with additional firmware: https://github.com/pH5/coda-bits More about this can be found here: https://imxdev.gitlab.io/tutorial/Decoding_video_with_a_mainline_kernel_on_i.MX6/

eSATA
In addition to enabling the Freescale PCIe driver and related SD support, if you want to connect an external eSATA device, there are two main "issues" to keep in mind:


 * Use a separate USB power source, since there is no power provided over eSATA (and the onboard USB is not enough)
 * You must add  to the kernel command line in  (or your )

Kodi
The live ebuild of Kodi (v18) can by now compiled without additional modifications.

If you want to use the etnaviv driver make sure to have a kernel with the VPU firmware loaded.

If you have docker running you can use the image https://hub.docker.com/r/slangenmaier/kodi/ to test it.

External resources

 * SolidRun Knowledge Base - CuBox-i – Getting Started
 * SolidRun Knowledge Base - Flashing an SD card
 * SolidRun Knowledge Base - i.MX6 Kernel
 * SolidRun Knowledge Base - Serial-Console USB->UART
 * Linux Wireless Wiki - Broadcom brcmfmac Firmware
 * NXP Community - HDMI goes to sleep
 * U-Boot mainline configuration
 * Wandboard

Open questions

 * open-source hardware-accelerated video driver
 * reverse engineered drivers