libubootenv setup

libubootenv setup

[Vipin Vijayan]

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Hi,
I am working on our custom board with dunfell version and we are using a
custom u-boot for the board. But when i try to use fw_printenv and
fw_setenv iam not being able to access those functionalities. Iam using
libubootenv for those specific functionalities .

iam adding libubootenv-bin in image_install and iam getting the fw_printenv
and fw_setenv in the /usr/bin folder

But when i use fw_printenv and fw_setenv iam getting an error,
Can't read from default
Can't read from file.

We are storing the environment variables in the spi flash /dev/mtd3

When i try hexdump i can find the variables present
But iam not being able to access it with fw_printenv and fw_setenv any
variable using fw_setenv

I should mention that fw_env.config is perfect and does not have any error
in it, because when we try to access those variables using another
fw_printenv, which we got from executing make in the git source , we are
getting the variables printed.

Also during build of the u-boot we are using a patch file which we got from
internet for its build succession, I dont know whether that patch
interferes with anything that hinders its function.

Iam attaching my fw_env.config and also the patch file i used for u-boot
along with this

As iam a beginner in this field, Iam not much aware of these
functionalities in detail. Please look in to the issue and any helps are
appreciated.

Regards,
*Vipin*

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From bdaa73a5b3923257add182b4ab8058dbfa33421b Mon Sep 17 00:00:00 2001
From: Stefano Babic <sbabic@denx.de>
Date: Wed, 13 Mar 2019 09:46:45 +0100
Subject: [PATCH] Add target to generate initial environment

The initial environment is linked to the u-boot binary. Modifying the
environment from User Space with the env tools requires that the tools
are always built together with the bootloader to be sure that they
contain the initial environment in case no environment is stored into
persistent storage or when a board boots with just the default
environment. This makes difficult for distros to provide a general
package to access the environment. A simpler way is if the tools are
generic for all boards and a configuration file is given to provide the
initial environment.

The patch just generates the initial environment by extracting it from
the compiled object. This file can then be used for tools in user space
to initialize the environment.

Signed-off-by: Stefano Babic <sbabic@denx.de>
---
 Makefile | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/Makefile b/Makefile
index 66a09ac900c3..f2c7bb6041a2 100644
--- a/Makefile
+++ b/Makefile
@@ -1977,6 +1977,13 @@ endif
 	$(build)=$(build-dir) $(@:.ko=.o)
 	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost
 
+quiet_cmd_genenv = GENENV $@
+cmd_genenv = $(OBJCOPY) --dump-section .rodata.default_environment=$@ env/common.o; \
+	sed --in-place -e 's/\x00/\x0A/g' $@
+
+u-boot-initial-env: u-boot.bin
+	$(call if_changed,genenv)
+
 # Consistency checks
 # ---------------------------------------------------------------------------
 

Re: [yocto] libubootenv setup

[Stefano Babic]

Hi Vipin,

On 03.06.23 12:29, Vipin Vijayan wrote:
> Hi,
> I am working on our custom board with dunfell version and we are using a 
> custom u-boot for the board. But when i try to use fw_printenv and 
> fw_setenv iam not being able to access those functionalities. Iam using 
> libubootenv for those specific functionalities .
> 
> iam adding libubootenv-bin in image_install and iam getting the 
> fw_printenv and fw_setenv in the /usr/bin folder
> 
> But when i use fw_printenv and fw_setenv iam getting an error,
> Can't read from default
> Can't read from file.
> 
> We are storing the environment variables in the spi flash /dev/mtd3
> 
> When i try hexdump i can find the variables present
> But iam not being able to access it with fw_printenv and fw_setenv any 
> variable using fw_setenv
> 
> I should mention that fw_env.config is perfect and does not have any 
> error in it, because when we try to access those variables using another 
> fw_printenv,

This is not a valid proof. Old tools have linked-in environment, and 
fw_printenv prints variables even if fw_env.config is not correct. If 
libuboot does not report the variables, the main reason is that your 
fw_env.config does not match the configuration in U-Boot.

To check this, you can set with old tool some variables, reboot your 
board and check if the variable can be read by U-Boot. If not, your 
fw_env.config is far away to be perfect.

> which we got from executing make in the git source , we are 
> getting the variables printed.
> 
> Also during build of the u-boot we are using a patch file which we got 
> from internet for its build succession, I dont know whether that patch 
> interferes with anything that hinders its function.

Patch was merged into U-Boot some years ago and you do not need it if 
your u-boot is not too old. You need to install u-boot-initial-env as 
well (this replaces the linked-in environment from old tool), it is part 
of u-boot-env package.

> 
> Iam attaching my fw_env.config

Only you can check if fw_env.config is correct.

> and also the patch file i used for u-boot 
> along with this

Patch was merged and part of U-Boot since 2019.07

> 
> As iam a beginner in this field, Iam not much aware of these 
> functionalities in detail. Please look in to the issue and any helps are 
> appreciated.
Best regards,
Stefano Babic

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