What is SW_GP1 purpose in i.MX RT 10xx family?

[embeddedev]

Could you tell me please what is the purpose of SW_GP1 and how can be used?

I understand that SW_GP2 (128 bits) can be used as AES128 key hardwired to DCP and BEE hardware module but I did not find anything in the documentation related to SW_GP1 (32 bit).
What is the difference between GP1 and SW_GP1? Beside general purpose usage, is there any special usage of SW_GP1 similar to SW_GP2?

Thank you for your support.

[stefanct]

One funny thing I just noticed: The low byte reads as 0xFF if I set EFUSE_PROG_SUPPLY_GATE. This makes as much sense as the documentation on this flag: nada.

The other 0x*80 fuses at 0x580 and 0x680 show the same behavior but are reserved.

[embeddedev]

Thank you Felipe for your reply. Do you know how to use SW_GP1 when it is locked by SW_GP1_LOCK? I mean, if this key is not hardwired to any crypto module then how could somebody use it when locked by SW_GP1_LOCK?

[embeddedev · Accepted solution]

Meanwhile I found following: "The SW_GP1 fuse doesn’t have a pre-defined purpose and isn’t hardwired to any of the crypto blocks. The SW_GP1_LOCK bit is a write and overwrite protection, so when it is set you can still read back the fuse value and use it (SW_GP1_LOCK isn’t a read lock)."

[FelipeGarcia]

Hi,

You can use it using fuse shadow memory footprint.

There is an specific location in OCOTP memory map that reflects the value of SW_GP1.

Best regards,

Felipe

[FelipeGarcia]

Hi,

SW_GP1 is a space in efuses to store keys. However, other than the size (32 bit) the other difference is that SW_GP1 cannot be used as AES key as is not supported as a key selection in the BEE module.

Best regards,

Felipe

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