Hi Eugeniu,
On Fri, 17 May 2019 at 08:46, Eugeniu Rosca erosca@de.adit-jv.com wrote:
'Bootloader Control Block' (BCB) is a well established term/acronym in the Android namespace which refers to a location in a dedicated raw (i.e. FS-unaware) flash (e.g. eMMC) partition, usually called "misc", which is used as media for exchanging messages between Android userspace (particularly recovery [1]) and an Android-capable bootloader.
On higher level, this allows implementing a subset of Android Bootloader Requirements [2], amongst which is the Android-specific bootloader flow [3]. Regardless how the latter is implemented in U-Boot ([3] being the most memorable example), reading/writing/dumping the BCB fields in the development process from inside the U-Boot is a convenient feature. Hence, make it available to the users.
Some usage examples of the new command recorded on R-Car H3ULCB-KF ('>>>' is an overlay on top of the original console output):
=> bcb bcb - Load/set/clear/test/dump/store Android BCB fields
Usage: bcb load <dev> <part> - load BCB from mmc <dev>:<part> bcb set <field> <val> - set BCB <field> to <val> bcb clear [<field>] - clear BCB <field> or all fields bcb test <field> <op> <val> - test BCB <field> against <val> bcb dump <field> - dump BCB <field> bcb store - store BCB back to mmc
Legend: <dev> - MMC device index containing the BCB partition <part> - MMC partition index or name containing the BCB <field> - one of {command,status,recovery,stage,reserved} <op> - the binary operator used in 'bcb test': '=' returns true if <val> matches the string stored in <field> '~' returns true if <val> matches a subset of <field>'s string <val> - string/text provided as input to bcb {set,test} NOTE: any ':' character in <val> will be replaced by line feed during 'bcb set' and used as separator by upper layers
=> bcb dump command Error: BCB not loaded!
Users must specify mmc device and partition before any other call
=> bcb load 1 misc => bcb load 1 1
The two calls are equivalent (assuming "misc" has index 1)
=> bcb dump command 00000000: 62 6f 6f 74 6f 6e 63 65 2d 73 68 65 6c 6c 00 72 bootonce-shell.r 00000010: 79 00 72 00 00 00 00 00 00 00 00 00 00 00 00 00 y.r.............
The output is in binary/string format for convenience The output size matches the size of inspected BCB field (32 bytes in case of 'command')
=> bcb test command = bootonce-shell && echo true true => bcb test command = bootonce-shell- && echo true => bcb test command = bootonce-shel && echo true
The '=' operator returns 'true' on perfect match
=> bcb test command ~ bootonce-shel && echo true true => bcb test command ~ bootonce-shell && echo true true
The '~' operator returns 'true' on substring match
=> bcb set command recovery => bcb dump command 00000000: 72 65 63 6f 76 65 72 79 00 73 68 65 6c 6c 00 72 recovery.shell.r 00000010: 79 00 72 00 00 00 00 00 00 00 00 00 00 00 00 00 y.r.............
The new value is NULL-terminated and stored in the BCB field
=> bcb set recovery "msg1:msg2:msg3" => bcb dump recovery 00000040: 6d 73 67 31 0a 6d 73 67 32 0a 6d 73 67 33 00 00 msg1.msg2.msg3.. 00000050: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00000060: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
--- snip --- Every ':' is replaced by line-feed '\n' (0xA). The latter is used as separator between individual commands by Android userspace
=> bcb store
Flush/store the BCB structure to MMC
[1] https://android.googlesource.com/platform/bootable/recovery [2] https://source.android.com/devices/bootloader [3] https://patchwork.ozlabs.org/patch/746835/ ("[U-Boot,5/6] Initial support for the Android Bootloader flow")
Signed-off-by: Eugeniu Rosca erosca@de.adit-jv.com
v2:
- [Heinrich Schuchardt] Implement sub-commands via U_BOOT_CMD_MKENT.
- Polished the code. Ensured no warnings returned by sparse, smatch, `cppcheck --force --enable=all --inconclusive`, make W=1.
- Tested on R-Car-H3-ES20 ULCB-KF.
v1:
cmd/Kconfig | 17 +++ cmd/Makefile | 1 + cmd/bcb.c | 330 +++++++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 348 insertions(+) create mode 100644 cmd/bcb.c
Where is this documented? Perhaps it should go in README.avb2?
Should it default to enabled if avb is used?
Regards, Simon