THIS IS AVAILABLE IN TIMESYS

link: https://linuxlink.timesys.com/docs/gsg

Introduction

This document will describe in detail the procedures for booting a Linux kernel image and mounting a root file system over NFS on the Freescale i.MX28 EVK.

Prerequisites

Host Requirements

To properly boot a board using software from Timesys, your host machine must meet the following requirements:

Modern GNU/Linux Distribution. While you can use nearly any modern Linux distribution released in the last 24 months, Timesys recommends one of the following:
- Ubuntu (Most recent release or LTS)
- Fedora (Most recent release)
An internet connection on the Development Host.
Root or sudo permission on the Development Host.
A copy of the Linux Kernel (uImage) and Root File System (rootfs.tar.gz) for the Target Board downloaded from Factory. These are found in the output directory of your online build, or in the directory build_armv5l-timesys-linux-<libc>/images/ on the command line.
If you are booting your root file system over the network, you will need two network cards installed and configured in the Development Host. One to communicate normally with your LAN/WAN while installing host packages, the other to communicate solely with the target board.
An available serial port on your Development Host.

Target Requirements

To boot the Freescale i.MX28 EVK, you will need the following items:

Freescale i.MX28 EVK Board
Serial NULL Modem Cable
Ethernet Crossover Cable or Ethernet hub/switch and Ethernet Patch Cables

Once you have all of the necessary components, you should perform the following steps:

Connect the debug port of the board to the serial port of your workstation using the null modem cable.
If you are using a cross-over cable, connect the Ethernet port of the board to the second Ethernet port of your workstation.
If you are using an Ethernet hub or switch, connect the board to the hub with a straight-through Ethernet cable, then connect the hub to the second Ethernet port of your workstation.
Connect the power supply to your board.

Preparing the Target

Configuring Serial Communication

The i.MX28EVK uses a serial debug port to communicate with the host machine. The commands discussed in this section are meant to be performed by a privileged user account. This requires the root login or prepending each command with sudo.

Using Minicom

Start minicom on your host machine in configuration mode. As root:

# minicom -o -s -w
A menu of configuration should appear. Use the Down-arrow key to scroll down and select the Serial port setup option, and press Enter.
Verify that the listed serial port is the same one that is connected to the target board. If it is not, press A, and enter the correct device. This is /dev/ttyS0 on most Linux distributions.
Set the Bps/Par/Bits option by pressing the letter E and using the next menu to set the appropriate values. You press the key that corresponds to the value 115200, then press Enter.
Set Hardware flow control to No using the F key.
Set Software flow control to No using the G key.
Press Enter to return to the main configuration menu, and then press Esc to exit this menu.
Reset the board, and wait for a moment. If you do not see output from the board, press Enter several times until you see the prompt. If you do not see any output from the board, and have verified that the serial terminal connection is setup correctly, contact your board vendor.

TIP: If you experience an error similar to Device /dev/ttyS0 is locked when starting minicom, it usually means that another process is using the serial port (which is usually another instance of minicom). You can find the process that is currently using the serial port by executing the following:

# fuser /dev/ttyS0 /dev/ttyS0: 28358

# ps 28358 PID TTY STAT TIME COMMAND 28923 pts/0 S+ 0:00 minicom

This process can also be killed directly with fuser as root. Please use this command with caution:

# fuser -k /dev/ttyS0

Using GNU Screen

To quickly connect to a board using Gnu Screen, execute the following:

# screen /dev/ttyS0 115200

For more information about using screen, please consult the man page, or view the manual online at http://www.gnu.org/software/screen/manual/screen.html

Configuring the Network Interface

Finding and Changing the MAC Address

The MAC address on the i.MX28EVK is set by the ethaddr environment variable in U-Boot. If ethaddr is not set, it can be set using the setenv command.
Example

> setenv ethaddr 12:34:56:78:9a:bc

The MAC Address can be found using the printenv command in U-Boot.
Example

> printenv baudrate=115200 bootfile="uImage" stdin=serial stdout=serial stderr=serial ethaddr=12:34:56:78:9a:bc

NOTE Once the MAC address has been set, it cannot be changed without destroying the entire U-Boot environment.

Changing the IP Address

The IP address can be set manually by modifying the ipaddr environment variable, or automatically using the dhcp or bootp commands.

Preparing the Host

Setting up the network

The commands discussed in this section are meant to be performed by a privileged user account. This requires the root login or prepending each command with sudo.

Identify the network adapter connecting the Host to the Target

Timesys only supports direct Ethernet connections from the development Host to the Target board. Ideally, the development Host would have two network adapters; one adapter to connect to your LAN, and one Ethernet card to connect directly to the Target board with a crossover cable or Ethernet hub. If your development Host only has one network interface it must be directly connected to the Target board. The Ethernet adapter connected directly to the target board must be:

Configured with a proper static IP address and Subnet Mask.
Connected directly to the target board with either a crossover cable or its own Ethernet hub.

From a command prompt issue the command:

# /sbin/ifconfig

Each interface will report its IP address, Subnet Mask, and Default Gateway information:

eth0 Link encap:Ethernet HWaddr 00:19:bb:49:ff:0e inet addr:192.168.3.244 Bcast:192.168.3.255 Mask:255.255.254.0 inet6 addr: fe80::219:bbff:fe49:ff0e/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:57214 errors:0 dropped:0 overruns:0 frame:0 TX packets:47272 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:43109083 (41.1 MB) TX bytes:6308206 (6.0 MB) Interrupt:16 eth1 Link encap:Ethernet HWaddr 00:10:b5:4a:c1:a9 inet addr:10.0.0.1 Bcast:10.0.0.255 Mask:255.0.0.0 UP BROADCAST MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:0 (0.0 B) TX bytes:0 (0.0 B) Interrupt:21 Base address:0x1100 lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:1974 errors:0 dropped:0 overruns:0 frame:0 TX packets:1974 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:226637 (221.3 KB) TX bytes:226637 (221.3 KB)

Note the IP address and Subnet Mask of the appropriate network connection. You will use this to configure the DHCP server.

Installing the server daemons on the development host

On Ubuntu 11.04 and newer:
# apt-get install xinetd tftp tftpd isc-dhcp-server \ nfs-kernel-server portmap
On Ubuntu 10.11 and older:
# apt-get install xinetd tftp tftpd dhcp3-server \ nfs-kernel-server portmap
NOTE: Older versions of Ubuntu use nfs-common and nfs-user-server in place of nfs-kernel-server
On Fedora Core:

# yum install xinetd tftp tftp-server dhcp nfs-utils

Important:
After installing these packages the DHCP server software may start automatically. Having the DHCP server running while you are connected to a LAN can interfere with the operation of other computers. After the DHCP service installs and starts issue these commands to stop the DHCP service and prevent it from starting automatically at boot:

To stop the dhcp service:
- On Ubuntu 11.04 and newer:
  
  # service isc-dhcp-server stop
- On Ubuntu 10.11 and older:
  
  # service dhcp3-server stop
- On Fedora Core:
  
  # /etc/init.d/dhcp stop
To prevent the service from starting automatically:
- On Ubuntu 11.04 and newer:
  
  # chmod 644 /etc/init.d/isc-dhcp-server
- On Ubuntu 10.11 and older:
  
  # chmod 644 /etc/init.d/dhcp3-server
- On Fedora Core:
  1. Click the System Menu
  2. Select Administration
  3. Select Services
  4. Select dhcpd
  5. Click the Customize button
  6. Uncheck Runlevel 2, 3, 4 and 5

Disable SELinux and Firewall on Fedora Core

On Fedora Core, SELinux and the firewall will interfere with many of the services that are needed to work with the target board. These should be disabled before continuing.
Generally Ubuntu does not have these services running by default.

Disable SELinux:
1. Click the System Menu
2. Select Administration
3. Select SELinux Management
4. Change System Default Enforcing Mode to Disabled
Disable Firewall:
1. Click the System Menu
2. Select Administration
3. Select Services
4. Select iptables
5. Click the Customize button
6. uncheck Runlevel 2, 3, 4 and 5

Setting up DHCP

Edit the dhcpd configuration file:
- On Ubuntu, edit /etc/dhcp/dhcpd.conf and include the following lines (note: on older versions of Ubuntu this file is at either /etc/dhcp3/dhcpd.conf or /etc/dhcpd.conf):
  
  subnet 10.0.0.0 netmask 255.0.0.0 { host targetboard { fixed-address 10.0.0.10; hardware ethernet 12:34:56:78:9a:bc; option root-path "/full/path/to/rfs"; filename "uImage"; } }
- On Fedora Core, edit /etc/dhcpd.conf and include the following lines:
  
  ddns-update-style ad-hoc; subnet 10.0.0.0 netmask 255.0.0.0 { host targetboard { fixed-address 10.0.0.10; hardware ethernet 12:34:56:78:9a:bc; option root-path "/full/path/to/rfs"; next-server 10.0.0.1; filename "uImage"; } }
Test the DHCP server on the network card that is connected to your development board. For this example assume eth1. This command will start the DHCP server in the foreground and output any status or error messages to the screen.
- On Ubuntu up to 12.04 LTS:
  
  # service dhcp3-server restart
- On Ubuntu 12.04 LTS and later:
  
  # service isc-dhcp-server restart
- On Fedora Core:
  
  # /usr/sbin/dhcpd -d eth1
- It is recommended to start the DHCP server in this manner each time you need to boot your Target board.

Setting up TFTP

Edit the xinetd.conf file
- On Ubuntu, edit /etc/xinetd.conf and add the following lines just above the line that reads includedir /etc/xinetd.d.
  
  service tftp { socket_type = dgram protocol = udp wait = yes user = root server = /usr/sbin/in.tftpd server_args = -s /tftpboot disable = no }
- On Fedora Core, the tftp-server package creates a /etc/xinetd.d/tftp file. Edit this file and change the disable line from yes to no. The contents of the file are:
  
  service tftp { socket_type = dgram protocol = udp wait = yes user = root server = /usr/sbin/in.tftpd server_args = -s /tftpboot disable = no per_source = 11 cps = 100 2 flags = IPv4 }
Create the /tftpboot folder if it does not exist:

# mkdir /tftpboot
Copy the kernel image to the /tftpboot directory:

# cp /path/to/kernel/image/uImage \ /tftpboot/uImage
NOTE Also copy other files that are required for booting, such as a device tree blob, to /tftpboot.
Restart the xinetd server with the following command:

# /etc/init.d/xinetd restart
Test the TFTP server with the following commands

# tftp localhost tftp> get uImage Received 1456898 bytes in 0.4 seconds tftp> quit
Set xinetd to start automatically on Fedora Core. Ubuntu users will skip this step.
1. Click the System Menu
2. Select Administration
3. Select Services
4. Select xinetd
5. Click the Customize button
6. Check Runlevel 2, 3, 4 and 5

Setting up NFS

As root, extract rootfs.tar.gz to a directory and note the path. This path will be referred to as /full/path/to/rfs in this document.

# mkdir /full/path/to/rfs # cd /full/path/to/rfs # sudo tar xvf rootfs.tar.gz
Export this path by editing /etc/exports to include a line similar to the following:

/full/path/to/rfs 10.0.0.10(rw,no_root_squash)
Restart the NFS services
- On Ubuntu issue the following commands in order:
  
  # service portmap stop # service nfs-kernel-server stop # service portmap start # service nfs-kernel-server start
  NOTE: Older versions of Ubuntu use nfs-common and nfs-user-server in place of nfs-kernel-server
- On Fedora Core:
  
  # /etc/init.d/nfs restart
Set nfsd to start automatically on Fedora Core. Ubuntu users will skip this step.
1. Click the System Menu
2. Select Administration
3. Select Services
4. Select NFS
5. Click the Customize button
6. Check Runlevel 2, 3, 4 and 5

Booting the Board

Set Environment Variables

You must set a few environment variables in order to boot the board over TFTP and DHCP. This is done with the setenv and saveenv commands in U-Boot. On the target, set the following environment variables:

Variable	Value
bootargs	console=ttyAM0,115200 ip=dhcp root=/dev/nfs rw
bootcmd	bootp\;bootm
loadaddr	42000000

If you are not using bootp to load the kernel, you must also specify the following values:

Variable	Value
serverip	10.0.0.1
ipaddr	10.0.0.10
bootfile	uImage
bootargs	console=ttyAM0,115200 ip=${ipaddr} root=/dev/nfs rw nfsroot=${serverip}:/full/path/to/rfs
bootcmd	tftp\;bootm 42000000

Example

> setenv bootargs console=ttyAM0,115200 ip=dhcp root=/dev/nfs rw > setenv bootcmd bootp\;bootm > setenv loadaddr 42000000 > saveenv

Load The Kernel

You can use bootp or tftp to load the kernel. Note that the DHCP server needs to be set up for bootp, and tftp is necessary for both.
Example

> bootp Speed: 100, full duplex BOOTP broadcast 1 Using eTSEC1 device TFTP from server 10.0.0.1; our IP address is 10.0.0.10 Filename 'uImage'. Load address: 42000000 Loading: ################################################################# ################################################################# ################################################## done Bytes transferred = 2632869 (282ca5 hex)

Boot the Kernel

The bootm command is used to boot the kernel. It loads the file that was previously uploaded using the bootp, dhcp, or tftp commands.
Example

> bootm ## Booting kernel from Legacy Image at 042000000 ... Image Name: Linux-2.6.31 Image Type: Linux Kernel Image (gzip compressed) Data Size: 2632805 Bytes = 2.5 MB Load Address: 00000000 Entry Point: 00000000 Verifying Checksum ... OK Uncompressing Kernel Image ... OK

Technical Knowledge Overview

Wednesday, 25 July 2018

Timesys Getting Started Guide for Freescale i.MX28 EVK