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A comment on AMD PSB Vendor Locks EPYC CPUs for Enhanced Security at a Cost. Parent comment

Re:AMD PSB Vendor Locks EPYC CPUs for Enhanced Security at a... by im3w1l on Tuesday September 08, 2020 @11:01PM (#24416511)
Oh the UEFI code is run by the main processor.. somehow I had always assumed it was running on some micro-processor on the mobo.
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Re:AMD PSB Vendor Locks EPYC CPUs for Enhanced Security at a... by 0zymandiass on Tuesday September 08, 2020 @11:22PM (#24416684)
Ah. Yeah.

The motherboard just loads BIOS/UEFI into a predefined memory address and then starts the CPU

This is a pretty good explanation https://manybutfinite.com/post/how-computers-boot-up/

> In a multi-processor or multi-core system one CPU is dynamically chosen to be the bootstrap processor (BSP) that runs all of the BIOS and kernel initialization code

These days, the "bootstrap processor" is a separate core that your OS can't see. On Intel it's the IME (running Minix) and on AMD it's the PSP (ARM TrustZone)

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