CL-SOM-iMX7: Linux: Getting started

Introduction

This article provides an introduction on how to install the Debian example root filesystem image on the CompuLab CL-SOM-iMX7 System-on-Module / Computer-on-Module eMMC internal storage device.

Preparation steps

• Obtain a PC workstation with a serial communication port.
• For networked installation you need to install a TFTP server on the host PC. For Windows machines we recommend TFTPD32 included in the Linux package for CL-SOM-iMX7 (link below).
• Download the Linux package for CL-SOM-iMX7 from CompuLab website. Unzip the package to a directory on your host workstation.
• All image files mentioned below can be found in the images subdirectory.
• Connect the host PC to the SBC-iMX7 base-board (connector P8) via the serial cable supplied with the evaluation kit.
• Start the terminal emulation software on your PC. Set baud rate to 115200 bps, 8 bit per frame, 1 stop bit, no parity, no flow control.
• Turn on the CL-SOM-iMX7 evaluation system. The U-Boot boot-loader will start and you will get a command prompt.

If the boot settings of your CL-SOM-iMX7 are different than the default, you may need to press and hold Ctrl-C while turning the CL-SOM-iMX7 on, in order to get command prompt.

Boot into the installation environment (ramdisk)

The first step in CL-SOM-iMX7 Linux installation is starting the installation environment (Linux kernel and Ramdisk image). This can be done using the following media:

• MMC/SD card
• USB storage device
• Network TFTP server

Using installation environment on MMC/SD card

• Copy kernel.img, imx7d-sbc-imx7.dtb, ramdisk.img and bootscr.img from Linux package for CL-SOM-iMX7 to the root directory on the first partition of the MMC/SD card. The partition can be formatted either ext2/3/4 or FAT file system.
• Insert the MMC/SD card into the SD socket (P9) on the SBC-iMX7.
• Use the following U-Boot commands to boot the installation environment on the CL-SOM-iMX7 evaluation system:

CL-SOM-iMX7 # mmc dev 0
CL-SOM-iMX7 # mmc rescan
CL-SOM-iMX7 # load mmc 0 ${loadaddr} bootscr.img
CL-SOM-iMX7 # source ${loadaddr}

• Continue to the Install Kernel and Debian Linux Images section.

Using installation environment on USB storage

• Copy kernel.img, imx7d-sbc-imx7.dtb and ramdisk.img from Linux package for CL-SOM-iMX7 to the root directory on the first partition of the USB storage. The partition can be formatted either ext2/3/4 or FAT file system.
• Insert the USB storage into either port on the dual USB host connector P6 of the SBC-iMX7.

SBC-iMX7 jumper E7 must be open

USB Boot

• Use the following U-Boot commands to boot the installation environment on a CL-SOM-iMX7 evaluation system:

CL-SOM-iMX7 # setenv fdt_file imx7d-sbc-imx7.dtb
CL-SOM-iMX7 # setenv ramdisk_addr 0x82000000
CL-SOM-iMX7 # setenv bootargs 'root=/dev/ram0 ramdisk_size=16384 console=ttymxc0,115200'
CL-SOM-iMX7 # usb start
CL-SOM-iMX7 # load usb 0 ${loadaddr} kernel.img && load usb 0 ${fdt_addr} ${fdt_file} && load usb 0 ${ramdisk_addr} ramdisk.img
CL-SOM-iMX7 # bootz ${loadaddr} ${ramdisk_addr} ${fdt_addr}

USB Boot using boot script

This approach can be used in order to avoid setting boot environment manually as in the example above.

• Use the following U-Boot commands to boot the installation environment on a CL-SOM-iMX7 evaluation system:

CL-SOM-iMX7 # usb start
CL-SOM-iMX7 # load usb 0 ${loadaddr} bootscr.img
CL-SOM-iMX7 # source ${loadaddr}

• Continue to the Install Kernel and Debian Linux Images section.

Using installation environment from TFTP server

• Connect the CL-SOM-iMX7 Ethernet port (connector P21 on the SBC-iMX7) to your local network.
• Put kernel.img, imx7d-sbc-imx7.dtb and ramdisk.img from Linux package for CL-SOM-iMX7 to a location accessible by the TFTP server:

  - On Windows machine: copy kernel.img, imx7d-sbc-imx7.dtb and ramdisk.img to the same folder and point the TFTP server to that folder

  - On Linux machine: copy kernel.img, imx7d-sbc-imx7.dtb and ramdisk.img to the TFTP server root directory, usually /tftpboot or /tftproot.

• You can use U-Boot dhcp command to obtain an IP address or manually set ipaddr environment variable:

CL-SOM-iMX7 # setenv ipaddr <CL-SOM-iMX7 ip address>

• Set the serverip environment variable:

CL-SOM-iMX7 # setenv serverip <tftp server host ip address>

• Use the following U-Boot commands to boot Linux on CL-SOM-iMX7:

CL-SOM-iMX7 # setenv loadaddr 0x80800000
CL-SOM-iMX7 # setenv fdt_addr 0x83000000
CL-SOM-iMX7 # setenv fdt_file imx7d-sbc-imx7.dtb
CL-SOM-iMX7 # setenv ramdisk_addr 0x82000000
CL-SOM-iMX7 # setenv bootargs 'root=/dev/ram0 rw ramdisk_size=16384 console=ttymxc0,115200 ip=dhcp'
CL-SOM-iMX7 # tftpboot ${loadaddr} kernel.img && tftpboot ${fdt_addr} ${fdt_file} && tftpboot ${ramdisk_addr} ramdisk.img
CL-SOM-iMX7 # bootz ${loadaddr} ${ramdisk_addr} ${fdt_addr}

• Continue to the Install Kernel and Debian Linux Images section.

Install Kernel and Debian Linux Images

After the ramdisk image is loaded the Linux command prompt will appear.

    Kernel release : Linux 3.14.52-cl-som-imx7-1.0


login[83]: root login on 'ttymxc0'
root@compulab:~#

The next step is installing the kernel and Debian Linux images. The following media can be used as a source for installation:

• MMC/SD Card
• USB storage device
• NFS drive

Debian Image

The latest Linux package for CL-SOM-iMX7 contain a Debian Sid rootfs image:

• debian-image.tar.bz2

Mount an MMC/SD Card

• Copy the debian-image.tar.bz2, imx7d-sbc-imx7.dtb and the zImage-cl-som-imx7 from the Linux package for CL-SOM-iMX7 to the root directory of any partition on the MMC/SD card. The partition can be formatted as either ext2/3/4 or FAT file system.
• Insert the MMC/SD card into the SD socket (P9) on the SBC-iMX7.
• The MMC/SD card is mounted automatically under /media/mmcblk0pX. Where X is the partition number.
• If for some reason the MMC/SD card hasn't been mounted automatically, use the following mount command:

root@compulab:~# mkdir -p /media/mmcblk0pX && mount /dev/mmcblk0pX /media/mmcblk0pX

• Continue to the Install Images section.

Mount a USB Storage Device

• Copy the debian-image.tar.bz2, imx7d-sbc-imx7.dtb and the zImage-cl-som-imx7 from the Linux package for CL-SOM-iMX7 to the root directory of any partition on the USB storage device. The partition can be formatted as either ext2/3/4 or FAT file system.
• Plug the USB storage device to either port on the dual USB host connector P6 of the SBC-iMX7.

SBC-iMX7 jumper E7 must be open

• The USB device is mounted automatically under /media/sdXY. Where X is the device letter and Y is the partition number.
• If for some reason the USB storage device hasn't been mounted automatically, use the following mount command:

root@compulab:~# mkdir -p /media/sdXY && mount /dev/sdXY /media/sdXY

• Continue to the Install Images section.

Mount an NFS drive

• Connect the CL-SOM-iMX7 Ethernet port (connector P21 on the SBC-iMX7) to your local network.
• Copy the debian-image.tar.bz2, imx7d-sbc-imx7.dtb and the zImage-cl-som-imx7 from the Linux package for CL-SOM-iMX7 to a directory exported through NFS.
• Obtain an IP address for the CL-SOM-iMX7:
  • Using DHCP:

    root@compulab:~# ifup eth0

  • If you do not have a DHCP server, you can set a static IP address using ifconfig:

    root@compulab:~# ifconfig eth0 <ip address>

• Mount the NFS share containing the zImage-cl-som-imx7 and the debian-image.tar.bz2 files:

root@compulab:~# mount -o nolock <host ip>:/path/to/nfs/share /mnt/net

• Continue to Install Images section.

Install Images

• In this subsection the term /mount/point can be:
  • /mnt/net if NFS is used
  • /media/mmcblk0pX if an MMC/SD card is used, where X is the partition number.
  • /media/sdXY if USB storage is used, where X is the USB drive letter and Y is the partition number.

Once the ramdisk image is loaded and the media containing the CL-SOM-iMX7 Kernel and Debian Linux images is mounted, the installation can be done on:

• MMC/SD or eMMC

Install on MMC/SD or eMMC

The below procedure will work on an empty MMC device only. If you have already used the MMC device, please delete all the partitions before proceeding.

• Define an environment variable that describes an MMC/SD device:

MMC/SD

root@compulab:~# export TARGET_DEVICE=mmcblk0

eMMC

root@compulab:~# export TARGET_DEVICE=mmcblk2

• Clean up the on the TARGET_DEVICE:

root@compulab:~# dd if=/dev/zero of=/dev/${TARGET_DEVICE} bs=1M count=1
root@compulab:~# hdparm -z /dev/${TARGET_DEVICE}

• Create two partitions for the Linux kernel (FAT32 100M) and root file system (EXT4 the rest of the disk) on the MMC device:

root@compulab:~# echo -e "n\np\n1\n\n+100M\na\n1\nt\nc\nn\np\n2\n\n\nw\neof\n" | fdisk /dev/${TARGET_DEVICE}

• Adjust the TARGET_DEVICE name:

root@compulab:~# TARGET_DEVICE=$(awk -v device=${TARGET_DEVICE} 'BEGIN {if (device~/mmc/) {part="p"}; print device part}')

• Format the first partition with FAT32 file system:

root@compulab:~# mkfs.vfat -n boot /dev/${TARGET_DEVICE}1

• Format the second partition with EXT4 file system:

root@compulab:~# mkfs.ext4 -L rootfs /dev/${TARGET_DEVICE}2

• Mount both partitions:

root@compulab:~# mkdir -p /media/boot && mount /dev/${TARGET_DEVICE}1 /media/boot
root@compulab:~# mkdir -p /media/rootfs && mount /dev/${TARGET_DEVICE}2 /media/rootfs

• Copy zImage-cl-som-imx7 and imx7d-sbc-imx7.dtb to the first (FAT) partition:

root@compulab:~# cp /mount/point/zImage-cl-som-imx7 /mount/point/imx7d*.dtb /media/boot && sync

• Extract the content of debian-image.tar.bz2 onto the second partition:

root@compulab:~# tar --numeric-owner -xpf /mount/point/debian-image.tar.bz2 -C /media/rootfs && sync

• Unmount both partitions:

root@compulab:~# umount /dev/${TARGET_DEVICE}1
root@compulab:~# umount /dev/${TARGET_DEVICE}2

• Continue to the After Installation section.

After Installation

If the boot settings of the CL-SOM-iMX7 are different than default, you may need to press and hold Ctrl-C while turning the CL-SOM-iMX7 on, in order to get command prompt.

Boot Environment

Common Environment Variables

CL-SOM-iMX7 # setenv bootdelay 3
CL-SOM-iMX7 # setenv image zImage-cl-som-imx7
CL-SOM-iMX7 # setenv loadaddr 0x80800000
CL-SOM-iMX7 # setenv fdt_file imx7d-sbc-imx7.dtb
CL-SOM-iMX7 # setenv fdt_addr 0x83000000

MMC/SD or eMMC

• mmcdev environment variable:

MMC

CL-SOM-iMX7 # setenv mmcdev 0
CL-SOM-iMX7 # setenv mmcblk 0

eMMC

CL-SOM-iMX7 # setenv mmcdev 1
CL-SOM-iMX7 # setenv mmcblk 2

• mmcroot environment variable:

CL-SOM-iMX7 # setenv mmcroot "/dev/mmcblk${mmcblk}p2 rootwait rw"

• Kernel and device tree loaders:

CL-SOM-iMX7 # setenv loadimage 'load mmc ${mmcdev}:${mmcpart} ${loadaddr} ${image}'
CL-SOM-iMX7 # setenv loadfdt 'load mmc ${mmcdev}:${mmcpart} ${fdt_addr} ${fdt_file}'

• bootargs environment variable:

CL-SOM-iMX7 # setenv bootargs "console=ttymxc0,115200 root=${mmcroot}"

Boot command

• Default boot command:

CL-SOM-iMX7 # setenv bootcmd 'run loadimage; run loadfdt; bootz ${loadaddr} - ${fdt_addr}'

• To boot Linux, type:

CL-SOM-iMX7 # saveenv
CL-SOM-iMX7 # run bootcmd

See also

• CL-SOM-iMX7: Linux: Debian
• CL-SOM-iMX7: Linux: Kernel
• Linux Development for ARM modules