Fuses: Difference between revisions
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If too many fuses are burnt the bootloader will panic immediately. | If too many fuses are burnt the bootloader will panic immediately. | ||
If too few are burnt, the bootloader will enable fuse programming and write the expected value to | If too few are burnt, the bootloader will enable fuse programming and write the expected value to fuses [[#reserved_odm6|reserved_odm6]] and [[#reserved_odm7|reserved_odm7]]. Afterwards, fuse programming is disabled and the panic value 0x21 is written to PMC_SCRATCH200 register (0x7000EC40). Finally, the watchdog timer is initialized and programmed to force a reset. | ||
On a subsequent boot, after the anti-downgrade fuses are checked again, the PMC_RST_STATUS register (0x7000E5B4) is checked and if set to 0x01 (watchdog reset) the PMC_SCRATCH200 register (0x7000EC40) will be checked for the panic value 0x21. | On a subsequent boot, after the anti-downgrade fuses are checked again, the PMC_RST_STATUS register (0x7000E5B4) is checked and if set to 0x01 (watchdog reset) the PMC_SCRATCH200 register (0x7000EC40) will be checked for the panic value 0x21. | ||
PMC_RST_STATUS will only be set back to 0 (power on reset) if the fuse count matches the new expected value, otherwise the system will panic. | PMC_RST_STATUS will only be set back to 0 (power on reset) if the fuse count matches the new expected value, otherwise the system will panic. | ||