[U-Boot] accessing eMMC boot partitions from U-Boot

[Stephen Warren]

On 03/13/2017 03:34 PM, Tim Harvey wrote:
> Greetings,
>
> I'm working with some boards with eMMC FLASH and understand that I can
> set the fields of the PARTITION_CONFIG with the 'mmc partconf' command
> to specify what partition is used for boot. Once I do that to set the
> boot0 partition for example, how can I access that  partition from
> within u-boot via mmc read/write? In Linux the kernel provides access
> to user/boot0/boot1/rpmb via different devices, but I don't see u-boot
> doing that.

The "mmc dev" command can be used to select which MMC device to operate 
on. The "typical" command "mmc dev 0" selects the main partition on MMC 
device 0 for later MMC-specific commands such as "mmc read". You can add 
an extra parameter to that command to request a specific HW partition, 
e.g. "mmc dev 0 1" selects boo0 of MMC device 0 and "mmc dev 0 2" 
selects boot1.

A similar naming scheme exists for commands that take a complete device 
specification each time. For example, "part list mmc 0" to list 
partitions in the main partition on MMC device 0, or "part list mmc 0.1" 
to list partitions on boot0 of MMC device 0.