View source for Running OpenOCD on Linux

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'''This guide contains general information on running OpenOCD, but all examples use the [[EmSys:STM32L Discovery | STM32L-Discovery]] board'''.
<!-- For examples using the {{BEAGLEBOARD_PRODUCTLINK}}, see [[Running OpenOCD on Linux with the Beagleboard]].'' -->

[[EmSys:OpenOCD |OpenOCD]] provides a command line interface for interacting with embedded devices. To use [[EmSys:OpenOCD |OpenOCD]] you will need to run it from the command line. This guide includes basic information about using the Ubuntu command line interface, the terminal window.

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If you are already proficient with the command line, you can find information specific to [[#OpenOCD Config Files | OpenOCD Config Files]] and [[#Telnet Connection | Telnet Connection]].
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==Opening the Command Prompt==

Open the '''Applications''' menu from the menu bar on your desktop, and choose '''Accessories > Terminal.''' Ubuntu should open blank window with white text and a prompt.

==Running OpenOCD==

Navigate to the directory containing your openocd executable. In the folder with the executable, make sure you also see three directories called '''interface/''', '''board/''', and '''target/'''. If you don't see these directories, create a new folder somewhere on your computer containing '''openocd''', '''interface/''', '''board/''', and '''target/'''. (If you have just compiled OpenOCD yourself, you can find the executable in '''openocd-/src''' or '''openocd-{{OPENOCD_VERNUM}}/src''', and the three directories you need in '''openocd/tcl''' or '''openocd-{{OPENOCD_VERNUM}}/tcl'''.

In the directory containing the openocd executable, type...<br /><br />

 sudo openocd -f path_to/cfg_file [-f path_to/other_cfg_file]<br /><br />

Replace ''path_to/cfg_file'' and so on with the .cfg files for your hardware devices. For example, to run OpenOCD for the STM32L-Discovery board, you would use:<br /><br />

 cd /home/USERNAME/{{OPENOCD_VERNUM}}-bin
 sudo ./openocd -f board/stm32ldiscovery.cfg<br />

==Telnet Connection==

[[EmSys:OpenOCD |OpenOCD]] runs as a daemon. It accepts connections from other programs, but does not provide any means for you to give it commands directly. Once [[EmSys:OpenOCD |OpenOCD]] is running on your computer you will need to connect to it through another program, such as '''telnet'''.

To run telnet and connect to [[EmSys:OpenOCD |OpenOCD]], open a new command prompt. From any directory, type:<br /><br />

 telnet localhost 4444<br /><br />

You may need to run telnet as root:<br /><br />

 sudo telnet localhost 4444<br /><br />

You should see a simple prompt ('''>'''). From this prompt you will be able to send commands to [[EmSys:OpenOCD |OpenOCD]]. To exit the telnet prompt, type '''shutdown'''.

==OpenOCD and Permissions==

[[EmSys:OpenOCD |OpenOCD]] needs administrator privileges to interact with your USB drivers. Even Linux users with administrator privileges do not typically log on with those privileges active. However, Linux provides commands to run another command as the root user. On Ubuntu, this command is ''sudo''. To run a program as root, type ''sudo'', then a space, then the name of the program. For example...<br /><br />

 ./openocd -f interface/stlink-v2.cfg -f target/stm32lx_stlink.cfg<br /><br />

...runs [[EmSys:OpenOCD |OpenOCD]] with your user permissions, and likely prevents [[EmSys:OpenOCD |OpenOCD]] from interacting with libUSB. However...<br /><br />

 sudo ./openocd -f interface/stlink-v2.cfg -f target/stm32lx_stlink.cfg<br /><br />

...runs [[EmSys:OpenOCD |OpenOCD]] as root, with full permission to access your USB drivers.

When you use the '''sudo''' command, Linux will prompt you for the root user's password. You can also configure Linux to allow [[EmSys:OpenOCD |OpenOCD]] to access specific hardware devices without ''sudo''. See [[EmSys:Accessing Devices without Sudo |Accessing Devices without Sudo]].

==Search Path==

[[EmSys:OpenOCD |OpenOCD]] searches in its own directory first for config files. This guide assumes that the '''openocd''' binary is in a directory containing three folders, called '''interface/''', '''board/''', and '''target/'''. If you have just compiled OpenOCD yourself, you will need to move the '''openocd''' executable somewhere where it can find '''interface/''', '''board/''', and '''target''', as described in the [[EmSys:Compiling_OpenOCD_v0.8.0_Linux#Preparing to Run_OpenOCD | Preparing to Run OpenOCD]].<br /><br />

You can also tell OpenOCD where to look for '''interface/''', '''board/''', and '''target/''' with the ''-s'' flag, like this:<br /><br />

 sudo openocd -s ../tcl -f interface/stlink-v2.cfg -f target/stm32lx_stlink.cfg<br /><br />

This would tell OpenOCD to look for '''interface/''' and '''target/''' one level up in a directory called '''tcl/'''. For more information, see [[EmSys:OpenOCD Config File Paths |OpenOCD Config File Paths]].<br /><br />

==OpenOCD Config Files==

Each time you use [[EmSys:OpenOCD |OpenOCD]] you will need to configure it by passing it paths to configuration files. In the [[EmSys:OpenOCD |OpenOCD]] {{OPENOCD_VERNUM}} release, these files are found in '''openocd-{{OPENOCD_VERNUM}}/tcl''' and its subdirectories. From the '''tcl''' directory, the configuration file for the STLink/V2 is at '''interface/stlink-v2.cfg'''. The file for the STM32L-Discoveryboard is at '''target/interface/stlink-v2.cfg'''. 

When you start [[EmSys:OpenOCD |OpenOCD]], you tell it to use the config files for your hardware with the '''-f''' switch, like this:<br /><br />

 sudo openocd -f path_to/cfg_file [-f path_to/other_cfg_file]<br /><br />

For example, suppose you want to run [[EmSys:OpenOCD |OpenOCD]] for the STM32L-Discovery board. The current directory contains the [[EmSys:OpenOCD |OpenOCD]] executable and the '''board''', '''interface''', and '''target''' directories provided with the OpenOCD source. You would type:<br /><br />

 sudo ./openocd -f interface/stlink-v2.cfg -f interface/stlink-v2.cfg<br /><br />

Be aware that config files may contain paths to other config files. For example ''board/stm32ldiscovery.cfg.cfg''', the config file for the STM32L-Discovery board, contains this line:<br /><br />

 source [find interface/stlink-v2.cfg]
 source [find target/stm32lx_stlink.cfg]<br /><br />

When you run [[EmSys:OpenOCD |OpenOCD]] with the '''board/stm32ldiscovery.cfg''' file, [[EmSys:OpenOCD |OpenOCD]] searches from the current directory for '''interface/stlink-v2.cfg'''. If the current directory does not contain [[EmSys:OpenOCD |OpenOCD]]'s '''interface''' directory, it may not find the '''stlink-v2.cfg''' file, or it may find a different '''stlink-v2.cfg''' file elsewhere on your system. You can avoid this by giving OpenOCD the path to your config files. For more information, see [[EmSys:OpenOCD Config File Paths |OpenOCD Config File Paths]].

If you have compiled OpenOCD yourself, the easiest way to avoid these issues is to copy the '''openocd''' binary from your '''openocd-{{OPENOCD_VERNUM}}/src''' directory to your '''openocd-{{OPENOCD_VERNUM}}/tcl''' directory. To run [[EmSys:OpenOCD |OpenOCD]], navigate to '''openocd-{{OPENOCD_VERNUM}}/tcl''' in the command terminal and run [[EmSys:OpenOCD |OpenOCD]] as above. You can also create a new directory anywhere on your system, and copy the '''openocd''' binary and the contents of '''openocd-{{OPENOCD_VERNUM}}/tcl''' to the new directory.

==Running Commands on Startup: the ''-c'' Flag==

You can instruct OpenOCD to run a command on startup with the ''-c'' flag. For example:<br /><br />

 sudo openocd -f interface/stlink-v2.cfg -c "jtag_khz 6000" -f target/stm32lx_stlink.cfg<br /><br />

The ''jtag_khz'' command sets the STLink/V2 clock speed. Starting OpenOCD like this does the following, in order:<br /><br />

*run commands in ''stlink-v2.cfg''
*run the OpenOCD command to set the stm32lx_stlink's clock speed
*run commands in ''stm32lx_stlink.cfg''.<br />

==See Also==
#[[EmSys:Accessing Devices without Sudo |Accessing Devices without sudo]]
#[[EmSys:OpenOCD Config File Paths |OpenOCD Config File Paths]]