Accessing U-Boot environment variables from Linux - Revision history

FabienM at 08:52, 14 September 2018

2018-09-14T08:52:27Z

2017-07-21T08:32:25Z

‎Setting and verifying an environment variable

2016-07-11T10:02:06Z

2015-09-30T07:48:38Z

‎Setting and verifying an environment variable

2015-02-18T14:51:48Z

‎Installation

2015-01-29T10:27:50Z

‎Installation

2015-01-29T10:24:11Z

2012-10-19T11:00:28Z

‎Installation

2012-10-19T10:58:32Z

‎Installation

2012-10-19T10:56:35Z

‎Installation

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 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''.
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 ==Links==
 * This page is an adaptation on this one: http://elinux.org/U-boot_environment_variables_in_linux

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 <pre class="apf">
 echo 0 > /sys/block/mmcblk2boot0/force_ro
 </pre>
 * Then set your variable:

← Older revision		Revision as of 10:02, 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 ==

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 === Setting and verifying an environment variable ===
 <pre class="apf">
    # fw_setenv mytestvariable abcdefg

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 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">
 # Configuration file for fw_(printenv/saveenv) utility.
@@ Line 31: / Line 31: @@
 </pre>
-* For the APF51 / U-Boot 2010.03:
+* For the [[APF51]] with U-Boot 2010.03:
 <pre class="apf">
 # Configuration file for fw_(printenv/saveenv) utility.
@@ Line 41: / Line 41: @@
 </pre>
-* For the APF9328 / U-Boot 1.3.4:
+* For the [[APF9328]] with U-Boot 1.3.4:
 <pre class="apf">
 # Configuration file for fw_(printenv/saveenv) utility.
@@ Line 51: / Line 51: @@
 </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">
 # Configuration file for fw_(printenv/saveenv) utility.
@@ Line 65: / Line 65: @@
 /dev/mtd2                 0x0000          0x20000           0x20000                 4
 </pre>
 == Usage ==

@@ Line 11: / Line 11: @@
 and then select the following option:
 <pre class="config">
-  Target filesystem options  --->
+  Hardware handling  --->
-      [*] Das U-Boot Boot Monitor  --->
+      [*] u-boot tools
-          [*]   fw_printenv tool in target
+          [*]   fw_printenv
 </pre>

@@ 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 ==
-{{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:

@@ Line 54: / Line 54: @@
 <pre class="apf">
 # 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.
-# 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
 /dev/mtd1                 0x0000          0x20000           0x20000                 4
 /dev/mtd2                 0x0000          0x20000           0x20000                 4