I predict that this will blow over, and won't be a big deal in a few years time once FOSS drivers for what is effectively just a new breed of TPM are released.
If in five years, it turns out I was wrong, I'll eat my hat. Although defining "my hat" by then might be difficult, as it'll probably be subscription based.
And non-x86 systems? Wasn't there a line of MS Surface devices where secure boot could not be disabled, and users were stuck with Windows? It feels careless to only care about x86, especially as other platforms proliferate.
In any case, lockdown is not the only threat that Trusted Computing presents. Remote attestation itself is dangerous. If we remove our x86 blinkers and look at the mobile world, we see it's already happening, with countless apps, including ones important to modern day life such as banking, refusing to run on rooted phones.
You may say, "Oh, I will use my x86 desktop system at home for Free Computing, and allow phones, consoles, tablets, surface devices, etc etc, to become locked down." Like the old free speech zones, this is a toothless freedom, tamed and neutered. The user-empowering Free Software you will write will have no users - they will be on locked devices.
The main issue these days is driver support. The PC platform was an anomaly in backwards compatibility, at least historically. I'm not arguing that it's going to be easy for FOSS. It's going to be an uphill battle, regardless of how locked down they are (and I'm just arguing that they won't be that locked down—see the recent M1 Macs for an example; Apple could easily have locked down those systems in exactly the same manner as iOS/iPadOS devices, but chose not to).
Linux drivers for Qualcomm SoCs don't have extensive ACPI bindings at this point in time though, making the use of a separate devicetree necessary for full functionality. This will be mostly ironed out with time I suppose.
Those are hardware dependent platform devices. Qualcomm didn’t have another option. (Nor do other manufacturers really)
On x86, a virtual PCIe bus abstraction is heavily used, which is not the case for those SoCs.
(And well, if Linux wants to boycott full support of their SoCs, their choice. They just can’t blame Qualcomm anymore at that point.)
Another thing of note is the use of a PEP (power management plug-in) in the OS instead of having power management done in AML. The ACPI spec allows a manufacturer to do this. It isn’t used only by Qualcomm, but is totally unsupported on Linux today.
> PEP (power management plug-in) in the OS […] ACPI spec allows a manufacturer to do this
Doing management in AML is almost the whole point of ACPI. Microsoft pushing this PEP thing into the ACPI spec is bad. This is the "letter" of ACPI now, unfortunately, but it's very much against the original "spirit" of ACPI :/
For PCIe indeed, but that’s not when the issues are present the most. There’s no standard register interface for integrated GPUs, modems…
> but it's very much against the original "spirit" of ACPI
Yup, it’s what Device Tree does too however, shifting this to the OS.
Another downside is trying to have a good driver-less boot scenario when PEPs are used, for the system to be able to go far enough until drivers can be installed. (N/A to Linux which is hostile to not in-tree drivers, but very much a concern on Windows)