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[FAQ] Redundant boot from eMMC boot partitions on AM62x

Hong Guan64
Guru 61855 points

1. booting from eMMC boot partition vs UDA partition
It is recommended to use eMMC boot partition for user's BootLoader (BL)
- eMMC boot partition is designed for bootloader user case
- it is possible to write-protect boot0/boot1 as necessary
- eMMC boot partition (boot0/boot1) are useful for SW update process for bootloader swapping
- ...

2. boot0/boot1 redundant boot auto-switch support by ROM
On eMMC boot mode, from which boot partition (boot0 or boot1) to boot eMMC depends on eMMC EXTCSD register[179], which adds external dependency for ROM to support redundant boot from eMMC boot partitions, and auto-switch between boot0/boot1 in case of boot failure is not currently supported in AM62x ROM.

The FAQ discusses one workaround option for switching between eMMC boot partitions (boot0/boot1) to support redundant boot with addition of backup boot media (i.e. SPI).

  • +1
    TI__Guru 61855 points

    The FAQ discusses a POC idea to support a robust boot strategy with a combination of primary boot media (+redundancy) + secondary boot media.
    Boot media configuration by BOOTMODE pins
    - primary boot media: eMMC boot partition (boot0/boot1) for regular BL
    - secondary backup boot media: SPI as an example for failure recovery management SW

    User scenario:
    - flash eMMC boot partition (boot0 & boot1) with regular BL, and configure eMMC EXTCSD register[179] to boot from boot0
    - flash failure recovery SW to SPI
    - ROM moves to backup boot media (i.e. SPI) in case ROM integrity check fails on BL from the current eMMC boot partition
    - recovery SW on SPI boots, and reconfigurs eMMC EXTCSD register[179] to boot from boot1, and issue SoC WarmReset
    - BL boots from eMMC boot1


    POC test log on AM62x-SK:
    a/. flashing
    - BOOTMODE[15:0]=0243 for SD boot
    - boot u-boot from SD card
    - flash u-boot from SDK 8.6 on SD to eMMC boot0 partition
    - configure eMMC EXTCSD register[179] to boot from boot0 by running "mmc partconf 0 1 1 1" cmd @u-boot
    - flash u-boot from SDK 8.6 on SD to OSPI-NOR
    - flash u-boot from SDK 9.0 on SD to eMMC boot1 partition

    b/. boot from eMMC boot partition (boot0)
    - reconfigure BOOTMODE[15:0]=0x18CB (eMMC boot partition + SPI) @u-boot
    - reset @u-boot
    - u-boot boots from boot0
    - stop @u-boot
    - erase tiboot3.bin from boot0 @u-boot
    - reset

    c/. reboot from SPI
    - ROM check integrity on tiboot3.bin from eMMC boot0
    - ROM falls through to boot from SPI
    - u-boot boots from SPI
    - stop @u-boot
    - reconfigurs eMMC EXTCSD register[179] to boot from boot1 by running "mmc partconf 0 1 2 1" cmd @u-boot
    - reset

    d/. reboot from boot1
    - u-boot boots from eMMC boot1

    Reference
    [1] [FAQ] AM64x/AM62x SoC redundant/recovery boot support in ROM booting R5 bootloader
    e2e.ti.com/.../faq-am64x-am62x-soc-redundant-recovery-boot-support-in-rom-booting-r5-bootloader

    [2] Re-configuring BOOTMODE[15:0] for ROM to load R5-BL by modifying CM register + WarmReset in SW
    In "5.2.3 Boot Process Flow in AM62x TRM"
    "The values of BOOTMODE[15:0] pins are latched into the Device Status register CTRLMMR_MAIN_DEVSTAT[15:0] by hardware as the device comes out of global cold reset, sampled after MCU_PORz deassertion."
    One option is listed below (referring to the above attached log) to reconfigure BOOTMODE[15:0] pins by modifying CM register + WarmReset in SW
    @u-boot
    - re-configure CTRLMMR_MAIN_DEVSTAT register @0x43000030
    - issue "reset", which is essentially SoC WARM_RESET
    => Upon SoC reboot from WarmReset, ROM
    - read the modified CTRLMMR_MAIN_DEVSTAT register as BOOTMODE[15:0]
    - load the R5-BL from the boot media specified by the the modified CTRLMMR_MAIN_DEVSTAT register.

    am62x_eMMC_SPI_flash_boot.log 
    U-Boot SPL 2021.01-g2ee8efd654 (Feb 24 2023 - 05:52:36 +0000)
SYSFW ABI: 3.1 (firmware rev 0x0008 '8.6.4--v08.06.04 (Chill Capybar')
SPL initial stack usage: 13424 bytes
Trying to boot from MMC2
Warning: Detected image signing certificate on GP device. Skipping certificate to prevent boot failure. This will fail if the image was also encrypted
Warning: Detected image signing certificate on GP device. Skipping certificate to prevent boot failure. This will fail if the image was also encrypted
Warning: Detected image signing certificate on GP device. Skipping certificate to prevent boot failure. This will fail if the image was also encrypted
Warning: Detected image signing certificate on GP device. Skipping certificate to prevent boot failure. This will fail if the image was also encrypted
Warning: Detected image signing certificate on GP device. Skipping certificate to prevent boot failure. This will fail if the image was also encrypted
Loading Environment from MMC... *** Warning - No MMC card found, using default environment

Starting ATF on ARM64 core...

NOTICE:  BL31: v2.8(release):v2.8-226-g2fcd408bb3-dirty
NOTICE:  BL31: Built : 05:06:58, Feb 24 2023

U-Boot SPL 2021.01-g2ee8efd654 (Feb 24 2023 - 05:29:33 +0000)
SYSFW ABI: 3.1 (firmware rev 0x0008 '8.6.4--v08.06.04 (Chill Capybar')
Trying to boot from MMC2
Warning: Detected image signing certificate on GP device. Skipping certificate to prevent boot failure. This will fail if the image was also encrypted
Warning: Detected image signing certificate on GP device. Skipping certificate to prevent boot failure. This will fail if the image was also encrypted


U-Boot 2021.01-g2ee8efd654 (Feb 24 2023 - 05:29:33 +0000)

SoC:   AM62X SR1.0 GP
Model: Texas Instruments AM625 SK
EEPROM not available at 0x50, trying to read at 0x51
Board: AM62-SKEVM rev E2
DRAM:  2 GiB
MMC:   mmc@fa10000: 0, mmc@fa00000: 1, mmc@fa20000: 2
Loading Environment from MMC... *** Warning - bad CRC, using default environment

In:    serial@2800000
Out:   serial@2800000
Err:   serial@2800000
Net:   eth0: ethernet@8000000port@1
Hit any key to stop autoboot:  2  0 
=> mmc list
mmc@fa10000: 0 (eMMC)
mmc@fa00000: 1
mmc@fa20000: 2
=> mmc dev 0 1
switch to partitions #1, OK
mmc0(part 1) is current device
=> load mmc 1 ${loadaddr} tiboot3.bin
332430 bytes read in 7 ms (45.3 MiB/s)
=> mmc write ${loadaddr} 0x0 0x400

MMC write: dev # 0, block # 0, count 1024 ... 1024 blocks written: OK
=> sf probe
SF: Detected s28hs512t with page size 256 Bytes, erase size 256 KiB, total 64 MiB
=> sf update $loadaddr 0x0 $filesize
device 0 offset 0x0, size 0x5128e

0 bytes written, 332430 bytes skipped in 0.15s, speed 17916227 B/s
=> load mmc 1 ${loadaddr} tispl.bin
961988 bytes read in 14 ms (65.5 MiB/s)
=> mmc write ${loadaddr} 0x400 0x1000.

MMC write: dev # 0, block # 1024, count 4096 ... 4096 blocks written: OK
=> sf update $loadaddr 0x80000 $filesize
device 0 offset 0x80000, size 0xeadc4

0 bytes written, 961988 bytes skipped in 0.32s, speed 28145020 B/s
=> load mmc 1 ${loadaddr} u-boot.img
897880 bytes read in 14 ms (61.2 MiB/s)
=> mmc write ${loadaddr} 0x1400 0x2000

MMC write: dev # 0, block # 5120, count 8192 ... 8192 blocks written: OK
=> sf update $loadaddr 0x280000 $filesize
device 0 offset 0x280000, size 0xdb358

0 bytes written, 897880 bytes skipped in 0.32s, speed 26269403 B/s
=> mmc dev 0 2
switch to partitions #2, OK
mmc0(part 2) is current device
=> ls mmc 1 am62_9.0.0.7
            ./
            ../
   291205   tiboot3-am62x-gp-evm.bin
   293794   tiboot3-am62x-hs-evm.bin
   293794   tiboot3-am62x-hs-fs-evm.bin
  1138011   tispl.bin
   962779   u-boot.img

5 file(s), 2 dir(s)

=> load mmc 1 ${loadaddr} am62_9.0.0.7/tiboot3-am62x-gp-evm.bin
291205 bytes read in 8 ms (34.7 MiB/s)
=> mmc write ${loadaddr} 0x0 0x400

MMC write: dev # 0, block # 0, count 1024 ... 1024 blocks written: OK
=> load mmc 1 ${loadaddr} am62_9.0.0.7/tispl.bin
1138011 bytes read in 17 ms (63.8 MiB/s)
=> mmc write ${loadaddr} 0x400 0x1000

MMC write: dev # 0, block # 1024, count 4096 ... 4096 blocks written: OK
=> load mmc 1 ${loadaddr} am62_9.0.0.7/u-boot.img
962779 bytes read in 16 ms (57.4 MiB/s)
=> mmc write ${loadaddr} 0x1400 0x2000

MMC write: dev # 0, block # 5120, count 8192 ... 8192 blocks written: OK
=> mmc partconf 0 1 1 1
=> mmc bootbus 0 2 0 0
=> md.l 0x43000030 1
43000030: 00000243                               C...
=> mw.l 0x43000030 0x18CB
=> md.l 0x43000030 1
43000030: 000018cb                               ....
=> reset
resetting ...

U-Boot SPL 2021.01-g2ee8efd654 (Feb 24 2023 - 05:52:36 +0000)
SYSFW ABI: 3.1 (firmware rev 0x0008 '8.6.4--v08.06.04 (Chill Capybar')
SPL initial stack usage: 13424 bytes
Trying to boot from MMC1
Warning: Detected image signing certificate on GP device. Skipping certificate to prevent boot failure. This will fail if the image was also encrypted
Warning: Detected image signing certificate on GP device. Skipping certificate to prevent boot failure. This will fail if the image was also encrypted
Warning: Detected image signing certificate on GP device. Skipping certificate to prevent boot failure. This will fail if the image was also encrypted
Warning: Detected image signing certificate on GP device. Skipping certificate to prevent boot failure. This will fail if the image was also encrypted
Warning: Detected image signing certificate on GP device. Skipping certificate to prevent boot failure. This will fail if the image was also encrypted
Loading Environment from MMC... *** Warning - bad CRC, using default environment

init_env from device 9 not supported!
Starting ATF on ARM64 core...

NOTICE:  BL31: v2.8(release):v2.8-226-g2fcd408bb3-dirty
NOTICE:  BL31: Built : 05:06:58, Feb 24 2023

U-Boot SPL 2021.01-g2ee8efd654 (Feb 24 2023 - 05:29:33 +0000)
SYSFW ABI: 3.1 (firmware rev 0x0008 '8.6.4--v08.06.04 (Chill Capybar')
Trying to boot from MMC1
Warning: Detected image signing certificate on GP device. Skipping certificate to prevent boot failure. This will fail if the image was also encrypted
Warning: Detected image signing certificate on GP device. Skipping certificate to prevent boot failure. This will fail if the image was also encrypted


U-Boot 2021.01-g2ee8efd654 (Feb 24 2023 - 05:29:33 +0000)

SoC:   AM62X SR1.0 GP
Model: Texas Instruments AM625 SK
EEPROM not available at 0x50, trying to read at 0x51
Board: AM62-SKEVM rev E2
DRAM:  2 GiB
MMC:   mmc@fa10000: 0, mmc@fa00000: 1, mmc@fa20000: 2
Loading Environment from MMC... *** Warning - bad CRC, using default environment

In:    serial@2800000
Out:   serial@2800000
Err:   serial@2800000
Net:   eth0: ethernet@8000000port@1
Hit any key to stop autoboot:  2  0 
=> mmc dev 0 1
switch to partitions #1, OK
mmc0(part 1) is current device
=> mmc read ${loadaddr} 0x0 0x100

MMC read: dev # 0, block # 0, count 256 ... 256 blocks read: OK
=> md.b ${loadaddr} 0x100
82000000: 30 82 04 94 30 82 03 fd a0 03 02 01 02 02 14 2f    0...0........../
82000010: 1b f7 6b 4c ef 63 65 52 32 b2 c7 33 b6 62 d0 1f    ..kL.ceR2..3.b..
82000020: db ed 06 30 0d 06 09 2a 86 48 86 f7 0d 01 01 0d    ...0...*.H......
82000030: 05 00 30 81 9d 31 0b 30 09 06 03 55 04 06 13 02    ..0..1.0...U....
82000040: 55 53 31 0b 30 09 06 03 55 04 08 0c 02 54 58 31    US1.0...U....TX1
82000050: 0f 30 0d 06 03 55 04 07 0c 06 44 61 6c 6c 61 73    .0...U....Dallas
82000060: 31 27 30 25 06 03 55 04 0a 0c 1e 54 65 78 61 73    1'0%..U....Texas
82000070: 20 49 6e 73 74 72 75 6d 65 6e 74 73 20 49 6e 63     Instruments Inc
82000080: 6f 72 70 6f 72 61 74 65 64 31 13 30 11 06 03 55    orporated1.0...U
82000090: 04 0b 0c 0a 50 72 6f 63 65 73 73 6f 72 73 31 13    ....Processors1.
820000a0: 30 11 06 03 55 04 03 0c 0a 54 49 20 53 75 70 70    0...U....TI Supp
820000b0: 6f 72 74 31 1d 30 1b 06 09 2a 86 48 86 f7 0d 01    ort1.0...*.H....
820000c0: 09 01 16 0e 73 75 70 70 6f 72 74 40 74 69 2e 63    ....support@ti.c
820000d0: 6f 6d 30 1e 17 0d 32 33 30 32 32 34 30 35 35 34    om0...2302240554
820000e0: 31 33 5a 17 0d 32 33 30 33 32 36 30 35 35 34 31    13Z..23032605541
820000f0: 33 5a 30 81 9d 31 0b 30 09 06 03 55 04 06 13 02    3Z0..1.0...U....
=> mmc erase 0 0x400

MMC erase: dev # 0, block # 0, count 1024 ... 1024 blocks erased: OK
=> mmc read ${loadaddr} 0x0 0x100

MMC read: dev # 0, block # 0, count 256 ... 256 blocks read: OK
=> md.b ${loadaddr} 0x100
82000000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
82000010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
82000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
82000030: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
82000040: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
82000050: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
82000060: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
82000070: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
82000080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
82000090: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
820000a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
820000b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
820000c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
820000d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
820000e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
820000f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
=> reset
resetting ...

U-Boot SPL 2021.01-g2ee8efd654 (Feb 24 2023 - 05:52:36 +0000)
SYSFW ABI: 3.1 (firmware rev 0x0008 '8.6.4--v08.06.04 (Chill Capybar')
SPL initial stack usage: 13424 bytes
Trying to boot from SPI
Warning: Detected image signing certificate on GP device. Skipping certificate to prevent boot failure. This will fail if the image was also encrypted
Warning: Detected image signing certificate on GP device. Skipping certificate to prevent boot failure. This will fail if the image was also encrypted
Warning: Detected image signing certificate on GP device. Skipping certificate to prevent boot failure. This will fail if the image was also encrypted
Warning: Detected image signing certificate on GP device. Skipping certificate to prevent boot failure. This will fail if the image was also encrypted
Warning: Detected image signing certificate on GP device. Skipping certificate to prevent boot failure. This will fail if the image was also encrypted
Loading Environment from MMC... *** Warning - No MMC card found, using default environment

Starting ATF on ARM64 core...

NOTICE:  BL31: v2.8(release):v2.8-226-g2fcd408bb3-dirty
NOTICE:  BL31: Built : 05:06:58, Feb 24 2023

U-Boot SPL 2021.01-g2ee8efd654 (Feb 24 2023 - 05:29:33 +0000)
SYSFW ABI: 3.1 (firmware rev 0x0008 '8.6.4--v08.06.04 (Chill Capybar')
Trying to boot from SPI
Warning: Detected image signing certificate on GP device. Skipping certificate to prevent boot failure. This will fail if the image was also encrypted
Warning: Detected image signing certificate on GP device. Skipping certificate to prevent boot failure. This will fail if the image was also encrypted


U-Boot 2021.01-g2ee8efd654 (Feb 24 2023 - 05:29:33 +0000)

SoC:   AM62X SR1.0 GP
Model: Texas Instruments AM625 SK
EEPROM not available at 0x50, trying to read at 0x51
Board: AM62-SKEVM rev E2
DRAM:  2 GiB
MMC:   mmc@fa10000: 0, mmc@fa00000: 1, mmc@fa20000: 2
Loading Environment from MMC... *** Warning - bad CRC, using default environment

In:    serial@2800000
Out:   serial@2800000
Err:   serial@2800000
Net:   eth0: ethernet@8000000port@1
Hit any key to stop autoboot:  2  0 
=> md.l 0x43000030 1
43000030: 000018cb                               ....
=> mmc partconf 0 1 2 1
=> reset
resetting ...

U-Boot SPL 2023.04-g756ba776d4 (Jul 13 2023 - 05:36:12 +0000)
SYSFW ABI: 3.1 (firmware rev 0x0009 '9.0.5--v09.00.05 (Kool Koala)')
SPL initial stack usage: 13376 bytes
Trying to boot from MMC1
Warning: Detected image signing certificate on GP device. Skipping certificate to prevent boot failure. This will fail if the image was also encrypted
Warning: Detected image signing certificate on GP device. Skipping certificate to prevent boot failure. This will fail if the image was also encrypted
Warning: Detected image signing certificate on GP device. Skipping certificate to prevent boot failure. This will fail if the image was also encrypted
Warning: Detected image signing certificate on GP device. Skipping certificate to prevent boot failure. This will fail if the image was also encrypted
Warning: Detected image signing certificate on GP device. Skipping certificate to prevent boot failure. This will fail if the image was also encrypted
Starting ATF on ARM64 core...

NOTICE:  BL31: v2.8(release):v2.8-226-g2fcd408bb3-dirty
NOTICE:  BL31: Built : 00:42:57, Jan 13 2023

U-Boot SPL 2023.04-g756ba776d4 (Jul 13 2023 - 05:36:12 +0000)
SYSFW ABI: 3.1 (firmware rev 0x0009 '9.0.5--v09.00.05 (Kool Koala)')
SPL initial stack usage: 1856 bytes
Error (-2): cannot determine file size
Trying to boot from MMC1
Warning: Detected image signing certificate on GP device. Skipping certificate to prevent boot failure. This will fail if the image was also encrypted
Warning: Detected image signing certificate on GP device. Skipping certificate to prevent boot failure. This will fail if the image was also encrypted


U-Boot 2023.04-g756ba776d4 (Jul 13 2023 - 05:36:12 +0000)

SoC:   AM62X SR1.0 GP
Model: Texas Instruments AM625 SK
EEPROM not available at 80, trying to read at 81
Board: AM62-SKEVM rev E2
DRAM:  2 GiB
Core:  71 devices, 31 uclasses, devicetree: separate
MMC:   mmc@fa10000: 0, mmc@fa00000: 1
Loading Environment from nowhere... OK
In:    serial
Out:   serial
Err:   serial
Net:   eth0: ethernet@8000000port@1
Hit any key to stop autoboot:  2  0 
=> md.l 0x43000030 1
43000030: 000018cb                             ....
=>