Firmware / Hypervisor / TZ kills Linux for touching at context bank registers

[Pierre-Hugues Husson]

On Mon, Jul 29, 2024 at 6:40 PM Marc Gonzalez <mgonzalez at freebox.fr> wrote:
>
> In my specific case, we just need to avoid using CB 12,
> because it is reserved by the FW under Linux.

Additionally, the way the vendor kernel handles that is by removing
the reset-on-probe ,
and by checking the state of each context bank on-boot.
So it creates on Linux boot a list of used context banks to never use.
This doesn't sound ideal because modprobe-rmmod loops could leak
context banks, but I think it's a reasonable behavior, as long as it's
gated with a device-tree flag.

Alternatively the way AngeloGioacchino did it (by hard-coding the CB)
could be kept as-is, but with a small tweak to help developers:
When doing the resets, log which CBs were in setup/valid state, so the
next developer hitting this issue has some pointers as to what to look
for.

Regards,