The compatablity of `locked` Eypc CPUs

[l.code]

Hi everyone,

I was wondering about the levels of compatibility related to locking on a locked server CPU.
Specifically, does the locking work at the brand level, server product line level, server model level, or the physical motherboard level?

The links below listed the product lines include categories such as Rack Servers with AMD CPUs and Tower Servers, each with various ThinkSystem server models and the their supported CPUs.
- AMD EPYC Processor Reference for Lenovo ThinkSystem Servers > Lenovo Press
- ThinkSystem servers | Lenovo Documentation


Example of brand-level compatibility:

• A locked Lenovo EPYC 7004 CPU can be used in any Lenovo ThinkSystem server that supports this CPU product line, regardless of product line or model.

Example of product-line-level compatibility:

• A locked Lenovo EPYC 7004 CPU pulled from a working ThinkSystem SR665 V3 can only be used in another SR665 V3, and not, for example, in an SR685a V3 server.

Or are there perhaps other factors to consider — such as the sales region or additional conditions?

Based on my research, PSB functions at the BIOS/firmware level, which suggests that compatibility is guaranteed at least at the model level.
However, a post, Lenovo Vendor Locking Ryzen-based Systems with AMD PSB (from STH) ,suggests that compatibility might extend to the brand level:
```text
A vendor-locked CPU can be installed in another system from the same vendor, but not swapped to a motherboard from a different vendor.
```

What are your thoughts or practical experiences?

 

[RolloZ170]

the lock is based on BIOS sign cert/key.
if the BIOS does not validate with the stored cert/key it is not executed.
vendors can use different cert/key in every product line.
but e.g. supermicro does not (does not use lock so far)

The PSP itself is a simple ARM Cortex processor core that is integrated directly into the CPU die.

The PSP begins execution in its boot ROM (programmed at manufacturing), which contains simple code that verifies and then loads the off-chip PSP bootloader located in the SPI flash.

 

[RolloZ170]

A vendor-locked CPU can be installed in another system from the same vendor, but not swapped to a motherboard from a different vendor.
```

if you cross flash the BIOS from the "locking" venfor to the target vendor it should POST.
in most cases that will not work because different layout of motherboards.