CM-T335: Linux: Getting started

Introduction

This article provides an introduction on how to install the following on the CompuLab CM-T335 System-on-Module / Computer-on-Module NAND internal storage device:

• Example user space (root filesystem) image.
• Linux kernel images.

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 CM-T335 (link below).
• Download the Linux package for CM-T335 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 SB-T335 base-board (connector P11) 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 CM-T335 evaluation system. The U-Boot boot-loader will start and you will get a command prompt.

If the boot settings of your CM-T335 are different than the default, you may need to press and hold Ctrl-C while turning the CM-T335 on, in order to get command prompt.

Boot into the installation environment (ramdisk)

The first step in CM-T335 Linux installation is starting the installation environment (Linux kernel and Ramdisk image). This can be done using one of the following media:

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

Using installation environment on MMC/SD card

• Copy the following files from Linux package for CM-T335 to the root directory on the first partition of the MMC/SD card:

  kernel.img, ramdisk.img, bootscr.img, debian-image.tar.bz2, uImage-cm-t335

The partition has to be formatted with either ext2/3/4 or FAT16/32 file system.

• Insert the MMC/SD card into the SD socket (P23) on the SB-T335.
• Use the following U-boot commands to boot the installation environment on the CM-T335:

CM-T335 # mmc rescan
CM-T335 # load mmc 0:1 80400000 bootscr.img
CM-T335 # source 80400000

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

Using installation environment on USB storage device

• Copy the following files from Linux package for CM-T335 to the root directory on the first partition on the USB storage device:

  kernel.img, ramdisk.img, bootscr.img, debian-image.tar.bz2, uImage-cm-t335

The partition has to be formatted with either ext2/3/4 or FAT16/32 file system.

• Plug the USB storage device into:
  • USB host connector (either P25, P26, P27 or P28) on SB-T335 if the CM-T335 module has U4 configuration or
  • USB OTG connector (P19) on SB-T335 if the CM-T335 module has U1 configuration
• Use the following U-boot commands to boot the installation environment on the CM-T335:

CM-T335 # usb start
CM-T335 # load usb 0:1 80400000 bootscr.img
CM-T335 # source 80400000

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

Using installation environment from TFTP server

• Connect the CM-T335 Ethernet port (connector P2 on the SB-T335) to your local network.
• Put kernel.img and ramdisk.img from Linux package for CM-T335 to a location accessible by the TFTP server:

  - On Windows machine: copy kernel.img and ramdisk.img to the same folder and point the TFTP server to that folder

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

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

CM-T335 # setenv ipaddr <CM-T335 ip address>

• Set the serverip environment variable and save the new environment:

CM-T335 # setenv serverip <tftp server host ip address>
CM-T335 # saveenv

• Use the following U-Boot commands to boot Linux on CM-T335:

CM-T335 # setenv bootargs "root=/dev/ram0 ramdisk_size=16384 console=ttyO0,115200"
CM-T335 # tftpboot 82000000 kernel.img && tftpboot 81000000 ramdisk.img
CM-T335 # bootm 82000000 81000000

• 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 line prompt will appear.
The next step is installing the kernel and Debian Linux images. Any one of the following media can be used as a source for installation:

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

Mount an MMC/SD Card

• Insert the MMC/SD card into the SD socket (P23) on the SB-T335.

The SB-T335 does not have an SD card detect functionality and therefore the micro SD card must be plugged in before the Linux boot process starts. If Linux has already booted before the SD card has been plugged in, then please repeat the Boot into the installation environment section.

• 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

• Plug the USB storage device to any USB host connector (either P25, P26, P27 or P28) on SB-T335 if the CM-T335 module has U4 configuration or to USB OTG connector (P19) on SB-T335 if the CM-T335 module has U1 configuration.
• 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 CM-T335 Ethernet port (connector P2 on the SB-T335) to your local network.
• Copy the debian-image.tar.bz2, and the uImage-cm-t335 from the Linux package for CM-T335 to a directory exported through NFS.
• Obtain an IP address for the CM-T335:
  • Using DHCP:

    root@compulab:~# ifup `basename /sys/class/net/eth?`

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

    root@compulab:~#  ifconfig `basename /sys/class/net/eth?` <ip address>

• Mount the NFS share containing the uImage-cm-t335, 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

Once the ramdisk image is loaded and the media containing the CM-T335 Kernel and Debian Linux images is mounted, the installation can proceed:

• 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.

• Format the NAND flash kernel partition and write the kernel image onto it:

root@compulab:~# flash_erase /dev/mtd5 0 0
root@compulab:~# nandwrite -p /dev/mtd5 /mount/point/uImage-cm-t335

• Format the NAND flash root filesystem partition:

root@compulab:~# ubiformat /dev/mtd6

• Attach the NAND flash root filesystem partition:

root@compulab:~# ubiattach -m 6 -d 0

• Create a ubi volume and name it "rootfs":

root@compulab:~# ubimkvol /dev/ubi0 -m -N rootfs

• Mount the ubi volume:

root@compulab:~# mkdir -p /media/rootfs && mount -t ubifs ubi0:rootfs /media/rootfs

• Extract the content of debian-image.tar.bz2 onto the /media/rootfs:

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

• Unmount the ubi volume:

root@compulab:~# umount /media/rootfs

• Reboot the CM-T335 Evaluation system.

After Installation

If the boot settings of the CM-T335 are different than default, you may need to press and hold Ctrl-C while turning the CM-T335 on, in order to get command prompt.

• Select video output. Default CM-T335 video output device is DVI. Other video output devices can be used as well.
  • To enable LCD video output:
    

    CM-T335 # setenv disp_type lcd

    
    
  • To enable LVDS video output:
    

    CM-T335 # setenv disp_type lvds

    
    
• Set the bootargs environment variable:

CM-T335 # setenv bootargs "console=ttyO0,115200n8 root=ubi0:rootfs rw rootfstype=ubifs ubi.mtd=rootfs cm_t335_disp=${disp_type}"

• To boot Linux, type:

CM-T335 # setenv bootdelay 3
CM-T335 # setenv bootcmd "nboot 82000000 nand0 900000; bootm"
CM-T335 # saveenv
CM-T335 # boot

See also

• CM-T335: Linux: Debian Legacy
• CM-T335: Linux: Kernel Legacy
• Linux: Development for ARM modules