Background:
ROM/HAB allocates certain memory region in Internal RAM (OCRAM) for HAB logs. This space is marked as reserved in Internal RAM memory map and must not be edited. This memory region is called HAB persistent memory. It contains certs, events and other HAB process related information.
Description:
HAB persistent memory is used by HAB to store audit logs i.e. logs of various events and status results generated from HAB library functions. HAB uses this memory region to search through existing events to report when requested through API call. HAB stores certificate information of the keys installed as reported in the CSF file.
In u-boot when the hab_status command is called, HAB searches through this memory region for tags of events generated and parses them to a human-readable format.
| Chipset | HAB Persistent Memory Address | Size |
|---|
| i.MX RT1020 / RT1050 / RT1015 | 0x20201000 | 0xB80 |
| i.MX6 S/DL/D/Q/DP/QP/UL/ULL/ULZ/SL/SLL/SX | 0x904000 | 0xB80 |
| i.MX7 S/D | 0x9049C0 | 0xB80 |
| i.MX7 ULP1 A7 B0 | 0x2F006840 | 0xB80 |
| i.MX7 ULP1 M4 B0 | 0x20008040 | 0xB80 |
| i.MX8 MQ (850D B0) | 0x9061C0 | 0xB80 |
| i.MX8 MQ (850D B1) | 0x9081C0 | 0x1200 |
| i.MX8 MM (845S A0) | 0x908040 | 0xB80 |
| i.MX8 MN (815S A0) | 0x908040 | 0x1200 |
| i.MX8 MP (865 A0) | 0x90d040 | 0x1200 |
| Vybrid F and R | 0x3F077000 | 0xB80 |
| i.MX 50 Family | 0xF8004000 | 0x900 |
| i.MX 53 Family | 0x1FFE4000 | 0x900 |
| i.MX 28 Family | 0x0001A800 | 0x600 |
Reading HAB events:
In order to check Events generated by HAB there are various methods that can be used:
1 - In u-boot, run hab_status command. Also, HAB persistent memory can be read and parsed to get these events (in case hab_status command isnt available)
md.b <0xPERSISTENT_MEMORY_ADDR> <0xSIZE>
2. Connect JTAG and dump the HAB persistent memory region.
3. If chip is in Serial download mode due to Authentication failure, USB Serial download protocol can be used to read HAB persistent memory region.
P.S. - Please email me for any suggestions/changes to this document.
P.P.S. - This document is up to date as of 10-18-2018
