Comment by worldsavior
9 hours ago
It's "Secure Page Table Monitor". https://support.apple.com/en-il/guide/security/sec8b776536b/.... The kernel requires it so they need to emulate SPTM.
9 hours ago
It's "Secure Page Table Monitor". https://support.apple.com/en-il/guide/security/sec8b776536b/.... The kernel requires it so they need to emulate SPTM.
This is not exactly correct. They wouldn’t need to emulate SPTM, since SPTM is already running. And to be very correct, SPTM is a “process” running in a separate privilege level to the regular privilege levels found on arm processors. The reason it’s a pain is because pre M4 the bootloader gave you complete control over the CPU, including the Apple-exclusive extensions like GLx, the special privilege levels e.g. SPTM is running at. Since M4 the bootloader handles that, so asahi team has to either cope with being dropped after GL is already initialized and locked down, or running in a mode with all of Apple extensions disabled. So it’s not a problem for running Linux, but it’s a problem for running macOS with a thin abstraction layer to intercept talking with devices like the GPU, which made reverse engineering for them significantly easier.
Thanks!