On 03/13/2017 06:54 PM, Ziyuan wrote:
hi Stephen,
On 03/14/2017 05:49 AM, 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.
The 4th of "mmc dev 0 1" is the *software* partition index, not the hw
partition index. AKA eMMC has four partitions: user
data/boot0/boot1/rpmb, I think Tim wanna to boot from other partition,
like boot0, right?
The fourth parameter is the HW partition number. See how cmd/mmc.c's
do_mmc_dev() passes this value to blk_select_hwpart_devnum(), then to
blk_select_hwpart().
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