Accessing U-Boot environment variables from Linux - Revision history

JulienB: /* Setting and verifying an environment variable */

2026-01-07T16:41:08Z

Setting and verifying an environment variable

← Older revision		Revision as of 18:41, 7 January 2026
Line 98:		Line 98:
	<pre class="apf">		<pre class="apf">
	echo 0 > /sys/block/mmcblk0boot0/force_ro		echo 0 > /sys/block/mmcblk0boot0/force_ro
			</pre>
			** On [[OPOS93]]:
			<pre class="apf">
			# echo 0 > /sys/block/mmcblk0boot1/force_ro
	</pre>		</pre>
	* Then set your variable:		* Then set your variable:

FabienM at 08:52, 14 September 2018

2018-09-14T08:52:27Z

@@ Line 1: / Line 1: @@
 U-Boot makes use of environment variables which can be read and set from the U-Boot command line with ''printenv'' and ''setenv''.  It can be helpful to read and set these variables from Linux as well, for ex. to remote control some U-Boot processes like software updates.  The U-Boot distribution has sources for these commands, named ''fw_printenv'' and ''fw_setenv''.
@@ Line 107: / Line 110: @@
 ==Links==
 * This page is an adaptation on this one: http://elinux.org/U-boot_environment_variables_in_linux

JulienB: /* Setting and verifying an environment variable */

2017-07-21T08:32:25Z

Setting and verifying an environment variable

← Older revision		Revision as of 10:32, 21 July 2017
Line 91:		Line 91:
	<pre class="apf">		<pre class="apf">
	echo 0 > /sys/block/mmcblk2boot0/force_ro		echo 0 > /sys/block/mmcblk2boot0/force_ro
			</pre>
			** On [[OPOS6UL]], you have to do this first:
			<pre class="apf">
			echo 0 > /sys/block/mmcblk0boot0/force_ro
	</pre>		</pre>
	* Then set your variable:		* Then set your variable:

SebastienSz at 10:02, 11 July 2016

2016-07-11T10:02:06Z

← Older revision		Revision as of 12:02, 11 July 2016
Line 67:		Line 67:

	* For the [[APF6]], as it uses an [[eMMC]] and no NOR/NAND Flash, there is a custom configuration file ''/etc/fw_env_apf6.config'' that should be moved to ''/etc/fw_env.config'' before going further.		* For the [[APF6]], as it uses an [[eMMC]] and no NOR/NAND Flash, there is a custom configuration file ''/etc/fw_env_apf6.config'' that should be moved to ''/etc/fw_env.config'' before going further.
			* For the [[OPOS6UL]], as it uses an [[eMMC]] and no NOR/NAND Flash, there is a custom configuration file ''/etc/fw_env_opos6ul.config'' that should be moved to ''/etc/fw_env.config'' before going further.

	== Usage ==		== Usage ==

JulienB: /* Setting and verifying an environment variable */

2015-09-30T07:48:38Z

Setting and verifying an environment variable

← Older revision		Revision as of 09:48, 30 September 2015
Line 86:		Line 86:

	=== Setting and verifying an environment variable ===		=== Setting and verifying an environment variable ===
			* Unlock Flash access (if needed):
			** On [[APF6]], you have to do this first:
			<pre class="apf">
			echo 0 > /sys/block/mmcblk2boot0/force_ro
			</pre>
			* Then set your variable:
	<pre class="apf">		<pre class="apf">
	# fw_setenv mytestvariable abcdefg		# fw_setenv mytestvariable abcdefg

JulienB: /* Installation */

2015-02-18T14:51:48Z

Installation

← Older revision		Revision as of 16:51, 18 February 2015
Line 21:		Line 21:
	To create this file, you need to know informations about where U-Boot stores its env variables. Specifically, you need the mtd device name, the device offset, the env size and the flash sector size. You can guess most of them by looking at ''/proc/mtd''.		To create this file, you need to know informations about where U-Boot stores its env variables. Specifically, you need the mtd device name, the device offset, the env size and the flash sector size. You can guess most of them by looking at ''/proc/mtd''.

	* For the APF27 / U-Boot 1.3.4:		* For the [[APF27]] with U-Boot 1.3.4:
	<pre class="apf">		<pre class="apf">
	# Configuration file for fw_(printenv/saveenv) utility.		# Configuration file for fw_(printenv/saveenv) utility.
Line 31:		Line 31:
	</pre>		</pre>

	* For the APF51 / U-Boot 2010.03:		* For the [[APF51]] with U-Boot 2010.03:
	<pre class="apf">		<pre class="apf">
	# Configuration file for fw_(printenv/saveenv) utility.		# Configuration file for fw_(printenv/saveenv) utility.
Line 41:		Line 41:
	</pre>		</pre>

	* For the APF9328 / U-Boot 1.3.4:		* For the [[APF9328]] with U-Boot 1.3.4:
	<pre class="apf">		<pre class="apf">
	# Configuration file for fw_(printenv/saveenv) utility.		# Configuration file for fw_(printenv/saveenv) utility.
Line 51:		Line 51:
	</pre>		</pre>

	* For ~~all~~ the ~~Armadeus boards~~ / U-Boot since 2012.04.01 (Armadeus-5.0~~...~~):		* For the [[APF9328]] / [[APF27]] / [[APF28]] / [[APF51]] since U-Boot since 2012.04.01 (Armadeus-5.0 and upper):
	<pre class="apf">		<pre class="apf">
	# Configuration file for fw_(printenv/saveenv) utility.		# Configuration file for fw_(printenv/saveenv) utility.
Line 65:		Line 65:
	/dev/mtd2 0x0000 0x20000 0x20000 4		/dev/mtd2 0x0000 0x20000 0x20000 4
	</pre>		</pre>

			* For the [[APF6]], as it uses an [[eMMC]] and no NOR/NAND Flash, there is a custom configuration file ''/etc/fw_env_apf6.config'' that should be moved to ''/etc/fw_env.config'' before going further.

	== Usage ==		== Usage ==

JulienB: /* Installation */

2015-01-29T10:27:50Z

Installation

← Older revision		Revision as of 12:27, 29 January 2015
Line 11:		Line 11:
	and then select the following option:		and then select the following option:
	<pre class="config">		<pre class="config">
	~~Target filesystem options~~ --->		Hardware handling --->
	[*] ~~Das U~~-~~Boot Boot Monitor --->~~		[*] u-boot tools
	[*] fw_printenv ~~tool in target~~		[*] fw_printenv
	</pre>		</pre>

JulienB at 10:24, 29 January 2015

2015-01-29T10:24:11Z

← Older revision		Revision as of 12:24, 29 January 2015
Line 1:		Line 1:
	U-Boot makes use of environment variables which can be read and set from the U-Boot command line with ''printenv'' and ''setenv''. It can be helpful to read and set these variables from Linux as well to remote control some U-Boot processes like software updates. The U-Boot distribution has sources for these commands, named ''fw_printenv'' and ''fw_setenv''.		U-Boot makes use of environment variables which can be read and set from the U-Boot command line with ''printenv'' and ''setenv''. It can be helpful to read and set these variables from Linux as well, for ex. to remote control some U-Boot processes like software updates. The U-Boot distribution has sources for these commands, named ''fw_printenv'' and ''fw_setenv''.

	== Installation ==		== Installation ==

	{{Note\|U-Boot tools are now installed and configured on ~~the target~~ since Armadeus 5.0. Therefore ~~this~~ installation procedure is only ~~usefull~~ for reference information.}}		{{Note\|U-Boot tools are now installed and configured on your APF since Armadeus 5.0. Therefore following installation procedure is only useful for reference information.}}

	Buildroot can automatically build these tools for you. You just have to:		Buildroot can automatically build these tools for you. You just have to:

Jorasse: /* Installation */

2012-10-19T11:00:28Z

Installation

← Older revision		Revision as of 13:00, 19 October 2012
Line 54:		Line 54:
	<pre class="apf">		<pre class="apf">
	# Configuration file for fw_(printenv/saveenv) utility.		# Configuration file for fw_(printenv/saveenv) utility.
	# Up to two entries are valid, in this case the ~~redundand~~		# Up to two entries are valid, in this case the redundant
	# environment sector is assumed present.		# environment sector is assumed present.
	# Notice, that the "Number of sectors" is ignored on NOR.		# Notice, that the "Number of sectors" is ignored on NOR and SPI-dataflash.
	# MTD device name Device offset Env. size Flash sector size Number of sectors		# Futhermore, if the Flash sector size is ommitted, this value is assumed to
			# be the same as the Environment size, which is valid for NOR and SPI-dataflash

			# Armadeus boards default environment configuration
			# MTD device name Device offset Env. size Flash sector size Number of sectors
	/dev/mtd1 0x0000 0x20000 0x20000 4		/dev/mtd1 0x0000 0x20000 0x20000 4
	/dev/mtd2 0x0000 0x20000 0x20000 4		/dev/mtd2 0x0000 0x20000 0x20000 4

Jorasse: /* Installation */

2012-10-19T10:58:32Z

Installation

← Older revision		Revision as of 12:58, 19 October 2012
Line 51:		Line 51:
	</pre>		</pre>

	* For all ~~armadeus~~ boards / U-Boot 2012.04.01:		* For all the Armadeus boards / U-Boot since 2012.04.01 (Armadeus-5.0...):
	<pre class="apf">		<pre class="apf">
	# Configuration file for fw_(printenv/saveenv) utility.		# Configuration file for fw_(printenv/saveenv) utility.