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... There 2 of those on eMMC and they are _NOT_ accessible in
this fashion. Neither they bear any FS on them. eMMC is _SPECIAL_ in that
respect -- although it does look like e.g. SD Card it has 2 additional
_HARDWARE_ boot partitions that none of other MMC devices have. Those are
invisible and they are _NOT_ a part of user partition.
I did try to push a patch that would've allowed to put U-Boot environment
into boot partitions so entire _USER_ partition would be free but
unfortunately it had been met with fierce resistance, as usual, as well as
my patch for writing a bootable U-Boot into boot NAND on iMX6. I will
probably make another attempt tomorrow or later this week as time permitted
against 2017-03 but will give up if this one also failed...
We do use U-Boot with those patches in production devices which we
manufacture many thousands of with no problems at all.
---
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