How to create EMMC partition using u-boot mmc commands?

Question

I'm using Raspberry PI Compute Module 4 for development. My RPI-cm4 has onboard EMMC 8GB memory. We are following below layout

For bootloader, we are using u-boot.

U-Boot> mmc list
mmcnr@7e300000: 1
mmc@7e340000: 0 (eMMC)

U-Boot> mmc part

Partition Map for MMC device 0  --   Partition Type: DOS

Part    Start Sector    Num Sectors     UUID            Type
  1     2048            247808          dda41d44-01     0c
  2     249856          60821504        dda41d44-02     83
U-Boot>

When I give mmc hw partition

U-Boot> mmc hwpartition
Partition configuration:
        No enhanced user data area
        No GP1 partition
        No GP2 partition
        No GP3 partition
        No GP4 partition
U-Boot> 

My requirement is to create a partition to support the following,

1. To store configuration files and these files will be used by the application services.
2. To support multi boot. Firmware upgrade from the multiple banks. When bank0 is not active, then kernel and rootfs should load from bank 1. And Also, I need to do all of this using boot script like automation, u-boot should do all check when creating partition using script.

My questions:

1. What is the best approach to store the config files. I saw software and hardware partition. What is the difference. If I create a partition part 3 in MMC device 0 like part 1 and 2, can I mount it as a file system and use it in application to access config files or do I really need hw partition?
2. How to automate the partition creation using u-boot script for multibank boot support?

I'm new to embedded domain.

Answer 1

I’m not really sure how to explain what the difference is between hardware and software partitions. I do know this, in your case a software partition would most likely fit for your needs, because you are storing configuration files.

For automating partitions for multibank, you could give a go at this script. I am not sure if it would work well or not.

# define
setenv active_bank 0

# define partition layout for each one of the banks
if test "${active_bank}" = "0"; then
    # Bank 0
    setenv partitions "mmc part 1 1; mmc part 2 0; mmc part 3 0 8000"
else
    # bank 1
    setenv partitions "mmc part 1 1; mmc part 2 0; mmc part 3 0 8000"
fi

# execute partition layout based on active bank
run partitions

# more config for banks
if test "${active_bank}" = "0"; then
    # config for bank 0
else
    # config for bank 1
fi

(Sorry for the vague answer)