fw_printenv(fw_setenv ) read from (write to ) which partition on sdcard for maaxboard(imx8mq_dev)?

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fw_printenv(fw_setenv ) read from (write to ) which partition on sdcard for maaxboard(imx8mq_dev)?

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gonewithwind-peter
Senior Contributor I

Hi all 

I want to solve my Qz here 

running uboot 's saveenv damage boot partition and can not boot again on maaxboard

https://community.nxp.com/t5/i-MX-Processors/running-uboot-s-saveenv-damage-boot-partition-and-can-n...

so I have to know that  fw_printenv(fw_setenv ) read from (write to ) which partition on sdcard?

I following the guide here: https://community.nxp.com/t5/i-MX-Processors-Knowledge-Base/Linux-fw-printenv-fw-setenv-to-access-U-...

I am play rauc , so I add one more addition rootfs. there are following partitions (using lsblck or gparted to show) in my bootable sdcard:

mmcblk0p1    (boot partition, kernel image, dtb uEnv.txt in it)   (notes: uboot image is msdos. can not show with lsblk)

mmcblk0p2 (rootfs_A)   normally mount at  /  after bootup

mmcblk0p3 (rootfs_B)    I want to switch it using rauc.

condition 1:

I tried first with   file: /etc/fw_env.conf  

/dev/mmcblk0  0x400000 0x1000

 

I can successfully run  fw_printenv and fw_setenv  ,

my Qz  1: at  /dev/mmcblk0  , fw_printenv(fw_setenv ) read from (write to ) which partition?    mmcblk0p1 ?  mmcblk0p2?

 

condition 2:

I tried secondly  with   file: /etc/fw_env.conf  

/dev/mmcblk0p1  0x400000 0x1000

 I can successfully run  fw_printenv and fw_setenv   and I can set different content environment variable with  condition 1.     and  both condition 1 and 2  can exist same time. if I change the file /etc/fw_env.conf  .I can  fw_printenv different content that I set before.

 

my Qz: so I condition 2 the environment variable is in which partition?  mmcblk0p1 ?  mmcblk0p2? ??? 

 

I was confused.

any help ?

Thank you very much.

 

 

 

 

 

 

 

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4 Replies

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jimmychan
NXP TechSupport
NXP TechSupport

Please try to dump the contents in the SD card. Check the changes are properly write to the correct offset in the storage.

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gonewithwind-peter
Senior Contributor I
it seem I set define CONFIG_ENV_OFFSET in .h file in uboot code is not work
#define CONFIG_ENV_OFFSET 0x2904000


it still savenev at 0x400000 (that is default setting for imx) (64 * SZ_64K) in sdcard and just damage the boot partition
it seems my setting is not working and can not change the default setting. but I wrote a wrong syntax to compile the code. it displayed error and I made sure it was compiled.
Let me try again.
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86 Views
gonewithwind-peter
Senior Contributor I

Hi
@jimmychan
thank you very much for your reply.
I think that is a good idea to dump the contents in the SD card to find the ENV position. but I do not how to dump.
before I tried to write c code to read /dev/mmcblk0 ,but the code not work. and I tried dd , but I did know what the options.
do you have more details to dump the contents in the SD card?
Thank you very much.

 

I have found the dd command how to dump, thanks

https://imxdev.gitlab.io/tutorial/How_to_dump_the_SDCard_content_to_an_image_file/

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gonewithwind-peter
Senior Contributor I

I find partial answer

 /etc/fw_env.conf 

/dev/mmcblk0  0x400000 0x1000 and the fw_printenv will damage the boot partition.

if /dev/mmcblk 0x2904000 0x1000    fw_printenv fw_setenv will work well. 

 

fw_printenv should write to absolute address  0x400000 (0x2904000) from sd card 0 sector 

I am searching saveenv in uboot command  to write where and calculate  how to set .h  file in uboot source code.

 

 

it seem I set define CONFIG_ENV_OFFSET in .h file in uboot code is not work
#define CONFIG_ENV_OFFSET 0x2904000


it still savenev at 0x400000 (that is default setting for imx) (64 * SZ_64K) in sdcard and just damage the boot partition
it seems my setting is not working and can not change the default setting. but I wrote a wrong syntax to compile the code. it displayed error and I made sure it was compiled.
Let me try again.

 

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