| High Assurance Boot (HAB) for i.MX6 CPUs | |
| To authenticate U-Boot only by the CPU there is no code required in | |
| U-Boot itself. However, the U-Boot image to be programmed into the | |
| boot media needs to be properly constructed, i.e. it must contain a | |
| proper Command Sequence File (CSF). | |
| The Initial Vector Table contains a pointer to the CSF. Please see | |
| doc/README.imximage for how to prepare u-boot.imx. | |
| The CSF itself is being generated by Freescale HAB tools. | |
| mkimage will output additional information about "HAB Blocks" | |
| which can be used in the Freescale tooling to authenticate U-Boot | |
| (entries in the CSF file). | |
| Image Type: Freescale IMX Boot Image | |
| Image Ver: 2 (i.MX53/6 compatible) | |
| Data Size: 327680 Bytes = 320.00 kB = 0.31 MB | |
| Load Address: 177ff420 | |
| Entry Point: 17800000 | |
| HAB Blocks: 177ff400 00000000 0004dc00 | |
| ^^^^^^^^ ^^^^^^^^ ^^^^^^^^ | |
| | | | | |
| | | -------- (1) | |
| | | | |
| | ------------------- (2) | |
| | | |
| --------------------------- (3) | |
| (1) Size of area in file u-boot.imx to sign | |
| This area should include the IVT, the Boot Data the DCD | |
| and U-Boot itself. | |
| (2) Start of area in u-boot.imx to sign | |
| (3) Start of area in RAM to authenticate | |
| CONFIG_SECURE_BOOT currently enables only an additional command | |
| 'hab_status' in U-Boot to retrieve the HAB status and events. This | |
| can be useful while developing and testing HAB. | |
| Commands to generate a signed U-Boot using Freescale HAB tools: | |
| cst --o U-Boot_CSF.bin < U-Boot.CSF | |
| objcopy -I binary -O binary --pad-to 0x2000 --gap-fill=0x00 \ | |
| U-Boot_CSF.bin U-Boot_CSF_pad.bin | |
| cat u-boot.imx U-Boot_CSF_pad.bin > u-boot-signed.imx | |
| NOTE: U-Boot_CSF.bin needs to be padded to the value specified in | |
| the imximage.cfg file. |