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

[Jaehoon Chung]

On 03/14/2017 01:44 PM, Stephen Warren wrote:
> On 03/13/2017 07:08 PM, Sergey Kubushyn wrote:
>> On Mon, 13 Mar 2017, Stephen Warren wrote:
>>
>>> 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.
>>
>> Unfortunately this has absolutely nothing to do with eMMC _BOOT_
>> partitions...
> 
> That's incorrect. See my other reply for details.

Yes, Stephen's comment is right.

> 
>> There 2 of those on eMMC and they are _NOT_ accessible in
>> this fashion. Neither they bear any FS on them.
> 
> The boot HW partitions are block storage just like any other. SW can place whatever data structures it wants into these HW partitions; the interpretation of any data stored here is up to the SW or HW that reads and interprets it, e.g. a SoC boot ROM. While many systems will place raw data here, others certainly do place SW partition tables, and perhaps even filesystems, in the HW partitions.

Also, agreed.

> 
> _______________________________________________
> U-Boot mailing list
> U-Boot at lists.denx.de
> https://lists.denx.de/listinfo/u-boot