From mboxrd@z Thu Jan  1 00:00:00 1970
From: Matthieu CASTET <matthieu.castet@parrot.com>
Subject: mmc-utils boot enable conflict with mmc_blk_part_switch
Date: Thu, 14 Aug 2014 11:11:05 +0200
Message-ID: <20140814111105.55aadaee@parrot.com>
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Cc: Chris Ball <chris@printf.net>, Ulf Hansson <ulf.hansson@linaro.org>

Hi,


Boot enable setting is enable with writting PARTITION_CONFIG ext csd.
But the kernel also write it in mmc_blk_part_switch.

This lead to weird result :


~ # mmc_utils extcsd read /dev/mmcblk0 | grep PARTITION_CONFIG
Boot configuration bytes [PARTITION_CONFIG: 0x00]
## no boot partition enabled
~ # mmc_utils boot enable 1 1 /dev/mmcblk0
~ # mmc_utils extcsd read /dev/mmcblk0 | grep PARTITION_CONFIG
Boot configuration bytes [PARTITION_CONFIG: 0x48]
## boot partition enabled
~ # dd if=/dev/mmcblk0boot0 of=/dev/null count=1
1+0 records in
1+0 records out
~ # mmc_utils extcsd read /dev/mmcblk0 | grep PARTITION_CONFIG
Boot configuration bytes [PARTITION_CONFIG: 0x01]
## kernel erased your boot partition config.


This is because the kernel have a cache of ext_csd in card->ext_csd and
is not aware of modification done by the mmc_utils.


Matthieu