| 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. |
