Quick Start Guide for BeagleBone Black. Table of Contents. by Brian Fraser Last update: Summer, 2015

Transcription

1 Quick Start Guide for BeagleBone Black by Brian Fraser Last update: Summer, 2015 This document guides the user through: 1. Installing Ubuntu in a virtual machine. 2. Connecting to the target using serial port and SSH. 3. Cross compile and run on the target. Table of Contents 1. Host OS Setup Screen Network Setup and SSH IP Addresses Direct connection setup (Optional) Directions for VirtualBox Directions for VM Ware (or Virtual Box) SSH NFS Cross-compile Setup Setup folders Build for Host vs Target Running via NFS...12 Note: This guide has not yet been tested in the SFU Surrey Linux Lab (SUR4080). Some changes may be needed. Formatting: 1. Commands starting with $ are Linux console commands on the host PC: $ echo "Hello world!" 2. Commands starting with # are Linux commands on the target (BeagleBone Black): # echo "Hello embedded world!" 3. Almost all commands are case sensitive. Revision History: TODO: Consider adding info on editing /etc/network/interfaces to make Ethernet over USB persistent, plus forwarding on host? Generated 09/09/14 1 / 16

2 1. Host OS Setup 1. Linux Ubuntu 14.04, 64bit, is the supported OS on the host PC for this class. Other versions of Linux or Unix derivatives may work, but are not supported by the instructor and TA. You can download Ubuntu from its official site: Also, a copy is available locally at SFU via 2. If you are running a non-linux OS, you may install Ubuntu in a virtual machine (VM). However, note that running inside a VM means one extra level of configuration is required. You may find it easier to run Linux natively on your computer as Ubuntu often installs well alongside existing operating systems. Under Windows or Mac OS, you can use VM Player or VirtualBox (both free). This YouTube playlist features three videos showing how to install a VM. To run a virtual machine in the SFU Lab (SUR 4080), install a VirtualBox VM on a USB 3.0 memory stick (3.0 is faster than USB 2.0) If you install Linux in a VM: Make the virtual hard drive large (~60gig). This gives plenty of room for extra build tools, libraries, and such. If you are installing to a flash drive, make the VM's hard drive no bigger than the free space on the flash drive. This will ensure that Linux is not trying to over-use the space on the flash disk. Give it as much RAM, video RAM, and processor access as possible; this will speed up Linux. Also enable 3d graphics acceleration for improved perfromance. 4. Troubleshooting: If having problems with Ubuntu's apt-get and dependencies, try following this guide: Note that if using the software-properties-gtk tool, you may need to run it with sudo from the command line: $ sudo software-properties-gtk 1 Notes on VM setup in the CSIL Surrey Labs: In Oracle VM VirtualBox Manager create a VM (or use an existing one), right-click on it and select Show in Explorer. Copy the entire folder onto your USB stick. Best to have your USB stick formatted to exfat so that it can be read under either Windows or Linux. On a different PC you want to develop on, in the VM Manager select Machine Add, and browse to your VM's folder on your USB stick. Note that you must be extra careful never to pull the USB stick when the VM is running because this could corrupt the state of your VM. You may also find it faster to shut-down and fully restart the VM than having the VM suspend to disk. Plus, this is one less thing to go wrong with writing to the USB drive. Note the top two USB ports on the front of the lab PCs are USB 3.0; the others are 2.0. When switching a VM between computers, some settings may need to be updated such as the network adapter used for bridging, shared folders, and so forth. Generated 09/09/14 2 / 16

3 2. Screen Screen is a tool which allows you to interact with a serial port through Linux. 1. TTL to USB adapter setup: Connect your TTL serial to USB adapter cable to your host. Plug the header onto the pins on the board. The black wire should be at the end towards the Ethernet connection. If using a virtual machine, you may need to map the adapter to the VM. In VMWare Player: Find the icon in upper right (on the tool bar) which reads future devices ttl232r-3v3. Right click it, and select the connect option. In Linux, just after connecting the device you can see if it has been configured correctly by typing: $ dmesg This shows messages produced by the kernel. You should see the last few lines being: [...] usb 2-2.1: new full-speed USB device number 5 using uhci_hcd [...] usb 2-2.1: New USB device found, idvendor=0403, idproduct=6001 [...] usb 2-2.1: New USB device strings: Mfr=1, Product=2, SerialNumber=3 [...] usb 2-2.1: Product: TTL232R-3V3 [...] usb 2-2.1: Manufacturer: FTDI [...] usb 2-2.1: SerialNumber: FTAKL988 [...] ftdi_sio 2-2.1:1.0: FTDI USB Serial Device converter detected [...] usb 2-2.1: Detected FT232RL [...] usb 2-2.1: Number of endpoints 2 [...] usb 2-2.1: Endpoint 1 MaxPacketSize 64 [...] usb 2-2.1: Endpoint 2 MaxPacketSize 64 [...] usb 2-2.1: Setting MaxPacketSize 64 [...] usb 2-2.1: FTDI USB Serial Device converter now attached to ttyusb0 This shows that the device is connected to /dev/ttyusb0. If you have multiple devices connected, yours may connect to ttyusb1 or higher. 2. Check /dev/ttyusb0 exists with the following command (expected output shown on next line): $ ls -al /dev/ttyusb0 crw-rw root dialout 188, 0 Sep 1 09:57 /dev/ttyusb0 3. Install Screen: $ sudo apt-get install screen 4. Start Screen with the following command: $ sudo screen /dev/ttyusb Where /dev/ttyusb0 is the port. May be ttyusb1, etc is the baud rate, or the speed of the connection is the default serial port speed for the BeagleBone Black. NOTE: If in SFU labs, you do not have root permission to host OS. Do not try any sudo commands in the host OS in the lab! Our IT staff will be automatically notified and they will contact you about it. Use sudo only on your PC or in the VM. If you want to use Screen inside the host OS in the lab, you should have access to /dev/ttyusb0 already so just type the command without sudo. Generated 09/09/14 3 / 16

4 5. Press Enter to see text on the serial port if you are connecting to a target device which is already running. User name is root and there is no password (Just press enter). Note that the root user's home directory is /root/, whereas most other users (such as one named brian) would be in the folder /home/brian/. This is the normal way Linux works with home directories. 6. Screen commands: Help: Ctrl-A then? Quit: Ctrl-A then \ 7. Trouble shooting After launching Screen, if you immediately see the message: [screen is terminating] it may mean that you do not have access to /dev/ttyusb0. Either change the permissions on /dev/ttyusb0 to be read/write by all users, or launch screen with sudo. Note that in the SFU labs, you do not have sudo (root) access. If you briefly see the following message at the bottom of the screen: Cannot exec 'ttyusb0': No such file or directory it likely means that you have not correctly connected your USB to TTL serial adapter, or if you are using a virtual machine, that you have not mapped it to the virtual machine correctly. If your Screen session locks up or begins dropping characters or corrupting text, here are some things to try: Ensure Screen is running with the correct baud rate (115200). Ensure your VM has more than the minimum video memory. Try increasing its access to 3D acceleration and the number of CPU cores (if possible). Try closing the screen session (Ctrl-A then \), and restarting the screen session. Sometimes under VirtualBox it seems that closing screen also locks up, but it then resolves within a minute and successfully quits screen. If the serial port seems to die in the VM, disconnect the serial cable from the VM and/or physically disconnect the USB cable. Perhaps try plugging it back into another USB slot. If trying to reconnect gives the error: Failed to attach the USB device FTDI TTL232R- 3V3... and... is busy with a previous request, with VirtualBox then you may need to kill the VBoxSVC.exe process in the Host OS, and/or reboot the host OS. Generated 09/09/14 4 / 16

5 3. Network Setup You need to have an internet connection to both your Linux development OS and the BBB. Plus, you need to have your development OS be able to connect to your BBB (we'll use SSH), and your BBB be able to connect to your development OS (we'll use NFS). There are a couple ways you can connect your devices. 1. Have your development computer and your BBB plugged into the same wired network, such as a home Ethernet network. 2. Have your BBB connect to your development computer using Ethernet over USB, and your development computer connect to the internet via WiFi or wired Ethernet. 3. Have your BBB directly connected to your development computer via a single Ethernet cable (not recommended). See the necessary section below for the option you are using. Section 3.4 covers some useful Linux networking commands. 3.1 Wired Ethernet Network This section assumes you are connecting your BBB to the same wired network that your development PC is connected to. 1. If using a virtual machine on the development computer, completely shutdown (power down, not just close/suspend) your virtual machine and change the network adapter type to Bridged instead of Network Address Translation (NAT). Under VMWare Player, select the VM and then Edit Virtual Machine Settings Network Adapter Bridged. OK to Replicate physical network connection state. Restart the VM. 2. Connect an Ethernet cable to the target board and have it get an IP address from your network's DHCP server (likely your home router). The board should automatically acquire a IP address in a few seconds (~30), but you may need to re-run either dhclient or udhcpc (depending on which is installed) to force it. You may need to reboot the target to have it acquire an IP address at startup: # reboot 3. Check the IP address of the target board using the serial connection: # ifconfig Generated 09/09/14 5 / 16

6 ~]# ifconfig eth0 Link encap:ethernet HWaddr c8:a0:30:aa:dd:a0 inet addr: Bcast: Mask: inet6 addr: fe80::caa0:30ff:feaa:dda0/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:22 errors:0 dropped:0 overruns:0 frame:0 TX packets:53 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:4176 (4.0 KiB) TX bytes:9945 (9.7 KiB) Interrupt:40 lo Link encap:local Loopback inet addr: Mask: inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:65536 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:0 RX bytes:0 (0.0 B) TX bytes:0 (0.0 B) usb0 Link encap:ethernet HWaddr 6a:41:80:a7:bf:db inet addr: Bcast: Mask: 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) Look for eth0's inet addr:, such as: inet addr: (Highlighted in above example) If you do not see eth0, it means the board has likely not yet found an IP address. Wait up to a minute longer for it to get an IP address. If it does not, double check all Ethernet cable connections and reboot the target. You may see (and ignore) some messages on the target such as: [ ] net eth0: phy 4a mdio:01 not found on slave 1 [ ] libphy: PHY 4a mdio:01 not found 4. Check the IP address of the Host PC: $ ifconfig Generated 09/09/14 6 / 16

7 $ ifconfig eth0 Link encap:ethernet HWaddr 00:0c:29:7f:47:bc inet addr: Bcast: Mask: inet6 addr: fe80::20c:29ff:fe7f:47bc/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets: errors:0 dropped:0 overruns:0 frame:0 TX packets:5079 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes: (41.7 MB) TX bytes: (1.1 MB) lo Link encap:local Loopback inet addr: Mask: inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:65536 Metric:1 RX packets:747 errors:0 dropped:0 overruns:0 frame:0 TX packets:747 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes: (277.1 KB) TX bytes: (277.1 KB) Find eth0's IP address, such as: inet addr: If running in a virtual machine, check the host OS's IP address as well: under Windows run ipconfig from the command line. 5. The addresses of the host and target (and host OS if running a VM) should be on the same subnet (have the first couple octets the same). If they are not the same then check the troubleshooting section below. Note that if your target device is plugged into a different network than your host PC they will be on different subnets. This may be the case in the SFU labs. 6. From the host PC, ping the Target. Command and output shown below. Press Ctrl-C to stop the pinging as needed. Replace the IP address with whatever address your target has. $ ping PING ( ) 56(84) bytes of data. 64 bytes from : icmp_seq=1 ttl=64 time=1.10 ms 64 bytes from : icmp_seq=2 ttl=64 time=0.585 ms 64 bytes from : icmp_seq=3 ttl=64 time=0.492 ms ^C ping statistics packets transmitted, 3 received, 0% packet loss, time 2001ms rtt min/avg/max/mdev = 0.492/0.727/1.105/0.270 ms 7. From the target, ping the host PC using your serial terminal. Command and output shown below. Press Ctrl-C to stop the pinging as needed. Replace the IP address with whatever address your host has. # ping PING ( ) 56(84) bytes of data. 64 bytes from : icmp_req=1 ttl=64 time=1.49 ms 64 bytes from : icmp_req=2 ttl=64 time=0.619 ms 64 bytes from : icmp_req=3 ttl=64 time=0.620 ms 64 bytes from : icmp_req=4 ttl=64 time=0.707 ms ^C ping statistics packets transmitted, 4 received, 0% packet loss, time 3004ms rtt min/avg/max/mdev = 0.619/0.861/1.499/0.370 ms Generated 09/09/14 7 / 16

8 8. Ensure your target and host can both access the internet: $ ping google.ca # ping google.ca If the ping fails, double check your network setup. 9. Troubleshooting: If the VM is not on same subnet as host OS, then make sure the VM's network adapter is configured for Bridged mode, instead of NAT. NAT uses the host OS's IP address for access to the network which will work fine for outgoing connections (such as browsing to Google), but not work for incomming connections (such as running an NFS server). You may need to restart the VM if you make any changes. If your target board (BBB) is on a different subnet than your host PC, double check that your host PC and target board are plugged into the same network. For example, you could have a problem if the host PC is connecting to a wireless network but the target device is connecting to a completely separate wired network. Reboot the target device to have it acquire a new IP address. 3.2 Ethernet over USB Expected setup is your host PC connected to the Internet via WiFi or Ethernet; host connected to target via a serial cable, and using a USB cable between host and target for emulated Ethernet. No Ethernet cable is required Initial Connection between Host and Target 1. Configure your VM to use NAT. Ensure that inside the VM you are able to access the Internet by pinging Google (for example). 2. Launch the VM. 3. Connect a USB cable from the host to the target. This cable was included with the BBB. Note that USB port will also power the target so to physically cycle the power you may need to disconnect both the USB and the power connector. You can run with just the USB power for most operations; however, the full power plug is needed to power the device when it is reflashing the system image or powering any external devices (such as USB devices). The USB cable required is a USB-A (host side) to USB-Mini (target side). It is not the TTL232-to-USB cable. 4. Map the USB connection to the VM. In VMware, use the Player button in the top left, go to Removable Devices Linux Foundation BeagleBoneBlack, and select to Connect. In Virtual Box, via VM's menu at the very top of the window select Devices USB Devices Circuitco BeagleBoneBlack 5. Check the network connection with ifconfig. It should show eth1 with an IP address Generated 09/09/14 8 / 16

9 6. The target will default to have a fixed IP address of via the emulated USB network connection (usb0). 7. Ping the host from the target, and the target from the host to ensure a working connection: $ ping # ping See previous section for more details on the commands. 8. Troubleshooting If the target reboots, the host will lose the Ethernet connection eth1. The connection will come back when the board finishes rebooting. If software on the target stops working, the Ethernet connection on the host may disappear. If unable to ping between the devices, run ifconfig on each to ensure correct IP addresses. Target's usb0 connection should be Host's eth1 connection should be Connecting Target to Internet 2 By following the above steps, you'll be able to ping between the host and the target. However, the target will not yet be able to access the internet. This section configures the host to allow the target to access the internet through its network connection. 1. Ensure your host PC (the Linux VM, likely) has access to the internet: $ ping google.ca 2. On the host PC, you should have two network adapters, likely named eth0 (actual network connection) and eth1 (virtual connection to target). Find them with: 2 Directions from Molloy (2014) Exploring BeagleBone, Ch2. Generated 09/09/14 9 / 16

10 $ ifconfig eth0 Link encap:ethernet HWaddr 08:00:27:a3:83:38 inet addr: Bcast: Mask: inet6 addr: fe80::a00:27ff:fea3:8338/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:2391 errors:0 dropped:0 overruns:0 frame:0 TX packets:707 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes: (2.6 MB) TX bytes:85463 (85.4 KB) eth1 Link encap:ethernet HWaddr c8:a0:30:aa:dd:a2 inet addr: Bcast: Mask: inet6 addr: fe80::caa0:30ff:feaa:dda2/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:3 errors:0 dropped:0 overruns:0 frame:0 TX packets:46 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:626 (626.0 B) TX bytes:10416 (10.4 KB) lo Link encap:local Loopback inet addr: Mask: inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:65536 Metric:1 RX packets:352 errors:0 dropped:0 overruns:0 frame:0 TX packets:352 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:27358 (27.3 KB) TX bytes:27358 (27.3 KB) 3. On the host, use the iptables program to configure the Linux kernel firewall rules: $ sudo iptables --table nat --append POSTROUTING --out-interface eth0 -j MASQUERADE $ sudo iptables --append FORWARD --in-interface eth1 -j ACCEPT 4. Turn on IP forwarding: $ sudo sh -c "echo 1 > /proc/sys/net/ipv4/ip_forward" 5. Configure the target to use the host (via Ethernet over USB) as the default gateway: # route add default gw You can check this succeeded by vewing the routing tables on the target using route: # route Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface default brian-virtualbo UG usb * U usb0 6. Check the target has an internet connection: # ping google.ca 7. These settings will not persist between reboots, so you must re-do all of these steps each time you reboot in order to re-enable the settings. You may be able to edit the /etc/network/interfaces file to make these settings permanent. Consult guides online for more information. Generated 09/09/14 10 / 16

11 8. Trouble shooting: If you rebooted either your target or host, you'll need to redo the settings on that device as the settings are not persistent. 3.3 Direct Ethernet Connection (Optional) You can directly connect the target device to a host PC using an Ethernet cable (or crossover). You may skip this section if you are connecting the BBB through either a wired Ethernet connection to a switch/router which supports DHCP, or using Ethernet over USB. If using a virtual machine, it is recommended that you use only Oracle VM VirtualBox for this configuration, otherwise it may not be possible to give your host PC and your target internet access. Expected connection is your PC (or virtual machine) is connected to the web via either WiFi or Ethernet, and you are going to connect an Ethernet cable directly from your PC to the target. (i.e., the target is connected to the host only, not to any network such as a router). 1. On the target, via a serial connection, set it to a static IP address: # ifconfig eth Note that this will revert back to DHCP when the target is rebooted. 2. Edit the settings for your virtual machine. You must have your VM powered down, not just suspended. Right click the VM in your Oracle VM VirtualBox Manager and select Settings. Under Network, enable Adapter 1 and set to NAT. This adapter will give your VM access to the internet through your host OS. Under Networking, enable Adapter 2 and set to Bridged. In the Name drop-down select your Ethernet adapter. This adapter will be the connection to the target. 3. Launch your virtual machine. 4. On the PC host, inside the VM, edit the networking settings Click networking icon in top right corner of Ubuntu. Select Edit Connections... Edit the connection for the NAT adapter from the host. Will likely be connection number 1 (may be listed second!). Under IPv4 Settings, ensure it is set to Automatic (DHCP) Edit the connection for your wired Ethernet. Will likely be the connection number 2 (may be listed first!). Under IPv4 Settings, click Add button and type in a new IP address: Netmask leave as 24 (which means 24 bits in the net mask, i.e., ). Leave Gateway as empty. Generated 09/09/14 11 / 16

12 Click Save Test your host's internet settings. Run ifconfig. eth0 will likely have an IP address in the range of and eth1 should have an IP address of Ping Google to prove you have a good internet connection. $ ping google.ca See troubleshooting below if there are any problems. 6. Ping the target from the host, and the host from the target. 7. Troubleshooting Run ifconfig on the target and host to ensure they have the correct addresses. If your VM cannot access the Internet (say pinging Google or installing via apt-get), then ensure that your host OS (Windows, for example) has a good connection to the Internet. Check that VirtualBox has enabled the network connection. In the VM's menu, select Devices Network Ensure that two network connections are listed and that both are enabled (filled background around the icon). Check network cable connected correctly. Check that the connections enabled in Linux. If ifconfig does not show eth0 or eth1, then enable the adapter using a command such as: $ sudo ifconfig eth0 up Double check the VM's networking settings. Ensure you select NAT and Bridged correctly. Try swapping the configuration of the two connections which you did in step 4. It is possible that they somehow became reversed. You can verify which VirtualBox connection maps to which connection in Linux by checking the MAC address of the connection. In VirtualBox settings for networking, select Adapter 1, and then expand the Advanced section. It will list a MAC address. Check this against the MAC addresses listed by ifconfig in the host PC's VM. 3.4 Linux Network Commands Here are some useful Linux commands for working with Ethernet (may need root access): Display Ethernet configuration information: $ ifconfig or $ ip addr Turn off, and turn on Ethernet connection (to cause it to redetect it): $ sudo ifconfig eth0 down $ sudo ifconfig eth0 up Generated 09/09/14 12 / 16

13 Or: $ sudo ifdown eth0 $ sudo ifup eth0 Run DHCP to acquire an IP address (only on some systems): $ dhclient Force a new (static) IP address: $ ifconfig eth Configure a static IP at boot for Debian based (Ubuntu) systems edit /etc/network/interfaces and set contents to: auto lo iface lo inet loopback # The primary network interface auto eth0 iface eth0 inet static address netmask broadcast gateway dns-nameservers Restart networking: $ sudo service networking restart Generated 09/09/14 13 / 16

14 4. Connecting via SSH and NFS 4.1 SSH 1. SSH from your host PC to the target device: $ ssh root@ Where the IP address is the address of the target device (BBB). The root@ tells SSH we want to connect as a specific user, the user named root, rather than the user name we logged into the host PC with. The root password is empty, so just hit enter. You may be asked to accept a security certificate; type yes. If you have made significant changes to the target device (such as reinstalling its operating system or file system), it may require you to remove a saved security certificate from the host PC before allowing you to SSH to the target. It will give you the command to execute in the error message. 2. Via the SSH connection, you can do anything would do via the serial connection. For example: # echo I am connected via SSH # cd /proc # cat uptime # cat cpuinfo 4.2 NFS Follow the steps in the NFS guide posted on the course website. Generated 09/09/14 14 / 16

15 5. Cross-compile Setup 5.1 Setup folders 1. On the host PC, create a directory for your work and for downloading (public): $ cd ~ $ mkdir -p cmpt433/work $ mkdir -p cmpt433/public Change /public to have global read/write permissions: $ chmod a+rw cmpt433/public Make sure none of your source code, makefiles, or the like is in the public directory. This directory can be read by everyone, so someone could take your work and hand it in, causing great problems for both students! It is OK, though, to have compiled programs and downloadable images (for U-Boot, the kernel, and the file system) in the public directory. 2. Install the cross-compiler and required tools: $ sudo apt-get install gcc-arm-linux-gnueabi $ sudo apt-get install binutils-arm-linux-gnueabi 3. Check tools installed with the following. It should display the compiler's version info: $ arm-linux-gnueabi-gcc version arm-linux-gnueabi-gcc (Ubuntu/Linaro ubuntu1) Copyright (C) 2012 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. 5.2 Build for Host vs Target 1. Create a new directory, called myapps, inside your work folder for all the applications you'll be writing: $ cd ~/cmpt433/work $ mkdir myapps 2. Create a quickstart folder inside myapps. 3. Create a HelloWorld.c program inside the quickstart folder. Use the gedit editor built into Ubuntu to edit the program. Note that the & at the end of a command makes it execute in the background, which here allows you to keep using your terminal while gedit is running. $ gedit HelloWorld.c & 4. Write the hello world program in C and save the file: #include <stdio.h> int main(char* args[]) { printf("hello embedded world!\n"); return 0; } 5. Compile and run the program for the host OS: $ gcc HelloWorld.c -o HelloWorld_Host $./HelloWorld_Host Generated 09/09/14 15 / 16

16 6. Compile the program for the target OS (Angstrom on the BBB): $ arm-linux-gnueabi-gcc HelloWorld.c -o HelloWorld_Target Try running the HelloWorld_Target application on the host OS. What happens? 7. Analyze the two executables you have just compiled using readelf: $ readelf -h HelloWorld_Host Machine: Advanced Micro Devices X86-64 Flags: 0x0 $ readelf -h HelloWorld_Target Machine: ARM Flags: 0x , has entry point, Version5 EABI, soft-float ABI Use this in the future when you need to identify which OS an executable is compiled for. 5.3 Running via NFS 1. Complete the NFS guide posted on the website to map the ~/cmpt433/public folder on the target board. 2. On the host PC, copy the HelloWorld_Target executable to the ~/cmpt433/public/ folder. $ cd ~/cmpt433/work/myapps/quickstart $ cp HelloWorld_Target ~/cmpt433/public/ 3. On the target, change to the mounted NFS folder: # cd /mnt/remote 4. On the target, run the executable: #./HelloWorld_Target 5. Congratulations! You've done some embedded development! 6. Repeat these steps for the HelloWorld_Host executable and see the result. Should the host version work on the target? Generated 09/09/14 16 / 16