How to create and flash separate images?

[cemal_cicekdes]

Hi all,

We are working on Yocto project on imx8 with 32GB eMMC flash. We managed to create separate partitions for /home and /userdata by creating a ".wks.in" file. We can flash the generated ".wic" image on eMMC via UUU tool and once the boards boots, we have /home and /userdata partitions on separate blocks as follow:

mmcblk0      179:0    0 29.7G  0 disk 
|-mmcblk0p1  179:1    0 44.3M  0 part /boot
|-mmcblk0p2  179:2    0  4.9G  0 part /
|-mmcblk0p3  179:3    0  150M  0 part /userdata
`-mmcblk0p4  179:4    0  120M  0 part /home

Now we need to find a way to create and flash images for /home and /userdata partitions separately and without touching other partitions. We created a .wic image for /userdata but we couldn't flash it via UUU tool nor dd command. UUU doesn't have an option for flashing the specific partition and dd command gives an error telling us that the image size is greater than partition size. (fixed size in wks file is 150Mb but the .wic image size is around 180Mb).

Is there a way in WIC to create and flash separate images for partitions?

Regards,

Cemal

[vinothkumars]

Hi @cemal_cicekdes ,

Did you done the separate flash ?

[cemal_cicekdes]

Hi @vinothkumars 

Unfortunately I couldn't find a way to separately flash a specific partition and I am not working on that NXP platform/project anymore.

Sorry for not being able to help.

Regards,

Cemal

[vinothkumars]

Thank you for the reply.

[cemal_cicekdes]

Hi,

Unfortunately flashing the full image doesn't help us. We need to keep the stored data on /userdata partition while updating other partitions, such as /home or /. How do you handle SW update on Yocto based projects? There must be a way to update specific partition.

Could you please give some information about SW update mechanism then?

Thanks&Regards,

Cemal

[cemal_cicekdes]

Hi again,

Could you please guide for SW update mechanism so that we can find a way to flash specific partitions?

Thanks,

Cemal

[gusarambula]

Hello Cemal,

The UUU is more suited to installing whole images, same as the dd, which is very useful when loading an image with the preset partitions but not as good as copying a specific partition, as a partition should already be in place and sizes must math.

We do not have much information on the. wic format, but there is some information on the Yocto Project documentation, which you probably have already checked. My recommendation would be creating a whole image with the partitions you require, so that they can be flashed by the UUU or the dd command, rather than flashing separate images or partition files.

Something like what the Yocto BSP does, similar to the .sdcard files (now replaced by .wic files) that setup all partition on an image that can be easily flashed on the destination.

Regards,