SAMA5D27 WLSOM eMMC parition Yocto

Moderator: nferre

uvijay
Posts: 5
Joined: Thu Jul 09, 2020 4:50 pm

SAMA5D27 WLSOM eMMC parition Yocto

Thu Aug 06, 2020 12:10 pm

Hi All,

I am using SAMA5D27 WLSOM board and using Yocto for building the images.
Able to generate the microchip-graphics images .wic format. I wanted to have partition on eMMC and was able to create some partitions using Yocto kick start file wks.

I am looking for raw or empty partition to store data as structure. and which can be accessible at u-boot and rootfs as well. Suggest me if any one was able to create raw or empty partition using kickstart file. Below is my kick start configuration.

Code: Select all

part /boot --source bootimg-partition --ondisk mmcblk0 --fstype=vfat --label boot --active --align 4 --size 16
part / --source rootfs --ondisk mmcblk0 --fstype=ext4 --label root --align 4 --size 600M 

# User data partition
part /userdata --ondisk mmcblk0 --fstype=ext4 --label userdata --align 4 --size 16M

part /rawdata --ondisk mmcblk0 --align 4 --label rawdata --size 50M
Thanks in advance,
Vijay
blue_z
Location: USA
Posts: 2154
Joined: Thu Apr 19, 2007 10:15 pm

Re: SAMA5D27 WLSOM eMMC parition Yocto

Tue Aug 11, 2020 9:48 pm

uvijay wrote: I am looking for raw or empty partition to store data as structure. and which can be accessible at u-boot and rootfs as well.
IMO that sounds like a dubious solution to some unspecified issue. You're creating yet another interface/dependency between U-Boot and the kernel.
Better hope that you have integrity checks that will identify/detect all possible cases of invalid/stale data.

Regards
uvijay
Posts: 5
Joined: Thu Jul 09, 2020 4:50 pm

Re: SAMA5D27 WLSOM eMMC parition Yocto

Tue Aug 18, 2020 4:12 pm

I wanted to store some apps env or user env data in a location which can be accessed at production time, uboot and in linux. Let me know your thoughts.
blue_z
Location: USA
Posts: 2154
Joined: Thu Apr 19, 2007 10:15 pm

Re: SAMA5D27 WLSOM eMMC parition Yocto

Wed Aug 19, 2020 9:03 pm

uvijay wrote: I wanted to store some apps env or user env data in a location which can be accessed at production time, uboot and in linux.
That confirms that you have a XY problem.

uvijay wrote: Let me know your thoughts.
You haven't provided any details.
Which way is the information flow?
How much data?

U-Boot can access files in a filesystem, and pass parameters using the kernel command line.
Linux has access to the saved U-Boot environment variables.
Yet you decided that the appropriate solution is to create a new storage method (and turned the X problem into the Y problem).

If you insist on using a "partition" for your solution to X, there are two boot partitions defined by the eMMC hardware that are typically unused.

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