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i.MX6SL Failure of Recovery Boot from SPI NOR After HAB fails on SD

Question asked by Wenbo Yang on May 1, 2017
Latest reply on May 26, 2017 by Wenbo Yang



Can you help to confirm when HAB authentication fails, the boot ROM of i.MX6SL will eventually jump to recovery SPI NOR flash? Or it just stuck there forever?


My evaluation on i.MX6SLEVK shows that it would stuck there, this is contradictory with what the "High level boot sequence" has illustrated.



1.  My intention is to use SD card as primary boot device, use HAB to check the data integrity of u-boot on SD card, if authentication fails, boot ROM should jump to SPI NOR;


2. The setup, note the "EEPROM Recovery Enable" bit is 1;


SW3/BOOTCFG1_0~7: 0000 0010

SW4/BOOTCFG2_0~7: 0011 0100

SW5/BOOTCFG4 _0~7: 00010010


3. The problem:

- Managed to go through the workflow of generating keys, burning the SRK fuses, compiling the HAB u-boot.imx, and then flashed the SD card and on-board 4MB NOR flash, and then "close" the SEC_CONFIG for HAB. Verified HAB works fine:


=> hab_status

Secure boot enabled

HAB Configuration: 0xcc, HAB State: 0x99


- But I found the yellow path doesn't work.  If I modify 1 bit in the u-boot image then flash it into SD card, then turn on the power switch, the board will get stuck forever, with nothing shown-up on serial console;


- Only the red path works, meaning I have to unplug the SD card then toggle the power switch of the EVK, then the boot ROM can jump to the SPI NOR to boot;



red path works, but yellow path doesn't work.