When changing the emmc, would a f/w downgrade possible?

[oaito]

Hi!

Wondering whether a f/w downgrade would be possible during a change of the emmc...

E.g.solving four issues in one go (dying of MCU storage, increasing airflow for cooling the MCU, going back to old cell voltage and charging rates @ my S85).

What do you think? Oaito.

 

[rooter]

You'd need to downgrade the firmware in the Spansion flash as well, else it will fail code-signing. You must not change the eMMC version without also changing the Spansion firmware. The Spansion uses CFI if you unsolder it.

I believe that the Fusee Gelee exploit tweaked for Tesla would allow access to everything without unsoldering, but for some reason that is being kept under wraps. No idea why, since the sploit can only be closed by changing hardware.

 

[laurynas]

So there must be relatively easy way to rollback to v8? If there is v8 firmware on p1 or p2, only need to unsolder SPANSION chip and dd boot.img into it?
Am I right? Is it enough to have right image on SPANSION chip to mount right partition? Or how it decides which partition to mount on boot?
Are there any other option to access SPANSION chip apart from unsoldering?
What if I will bind mount /usr/deploy directory with content from version 8, then restart cid-updater and try to run factory-redeploy? Will it allow v8 cid-updater to run on v9? Anybody have tried it?