[yjftsjthsd-h]

> Will you PLEASE stop promoting UEFI and ACPI?! These are closed-source blobs that the manufacturers will never update and have complete control over the system at ring -2. Why would you even consider it?

Well, no, UEFI can have proprietary implementations, but nothing prevents just shipping edk2.

Conversely, there are so many phones with devicetree... and proprietary blobs controlling boot and running beneath ring 0. You're kinda pointing out a real problem, but confusing it with a different part of the stack.

[M95D]

> there are so many phones with devicetree... and proprietary blobs controlling boot and running beneath ring 0

It's not the same!

A bootloader, once it loads the kernel and executes it, is overwritten in memory. No trace of it remains while the sistem is running - until the next boot. UEFI / ACPI / SMM continue to execute on the CPU after it finished booting, "under" the kernel, preempting it as they please.

[yjftsjthsd-h]

I mean, it's not uniformly literally technically identical, but yes, an Android phone running its OS in ring 0 while other OSs run in other VMs on top of the EL2 (ring -1) hypervisor under the supervision of the Secure Monitor in L3 (ring -2) is very much in the same boat.

Suggested reading:

* https://www.maven-silicon.com/blog/privilege-levels-in-arm-a...

* https://projectzero.google/2017/02/lifting-hyper-visor-bypas...

* https://en.wikipedia.org/wiki/ARM_architecture_family#Securi...

* https://docs.samsungknox.com/admin/fundamentals/whitepaper/s... (in which Samsung uses firmware running under the kernel to protect against kernel exploits)

[M95D]

Oh, I didn't know that!

There goes freedom in the ARM world too.