Hi

 

We've made a patch for the current a64 megous 5.10 kernel which enables writing to the 2K SID/Efuse security area of the A64/R18 processor.

Our initial investigations have found that the A64 doesn't seem to match the tables found in the SID Register Guide, however we've proceeded to perform various write tests and are presenting our results here for anyone that may found it useful in further development. There shouldn't be any issues using the same patch in the 5.14 kernel, as the driver code is still the same. The patch won't be pushed upstream, and is for dev purposes only, as the original intend of the driver is to be read-only. (This is EFUSE area )

 

The armbian branch with the patch is on github

 

Our tests have resulted in some erratic behavior with the registers as has previously been reported by Icenowy during her tests.Additionally we have only found a total of 32 fragmented bytes that we've been able to write to.
A reply to this post shortly will show a map of the writable efuse area that we found.

 

Gavin B

Moved