This is the same hardware as a PC, but TPM and UEFI “Secure Boot” happen way, way later in the boot process and aren’t present here; this is the hardware root of trust, in this case the AMD PSP boot firmware, which runs on an ARM system alongside the x86 cores. Intel’s version is called Boot Guard and runs on a combination of x86 sub-cores (TXE) and ME.
Interestingly, I've heard on the grapevine that AMD PSP was originally from the hardware security in the Xbox One (ie. the third line of Xboxes), hence why it's an ARM core. And it's also another branch in the lineage that also includes the Pluton security module.
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This is the same hardware as a PC, but TPM and UEFI “Secure Boot” happen way, way later in the boot process and aren’t present here; this is the hardware root of trust, in this case the AMD PSP boot firmware, which runs on an ARM system alongside the x86 cores. Intel’s version is called Boot Guard and runs on a combination of x86 sub-cores (TXE) and ME.
Interestingly, I've heard on the grapevine that AMD PSP was originally from the hardware security in the Xbox One (ie. the third line of Xboxes), hence why it's an ARM core. And it's also another branch in the lineage that also includes the Pluton security module.