Re: AMD zen microcode updates breaks boot

[Jens Axboe]

On 10/18/24 10:45 AM, Dr. David Alan Gilbert wrote:
> * Borislav Petkov (bp@xxxxxxxxx) wrote:
>> On Fri, Oct 18, 2024 at 07:30:15AM -0600, Jens Axboe wrote:
>>> At least on mine, the BIOS has an option that says something like "L3
>>> cache as numa domain", which is on and why there's 32 nodes on that box.
>>> It's pretty handy for testing since there's a crap ton of CPUs, as it
>>> makes affinity handling easier.
>>
>> Right, so two boxes I tested with this:
>>
>> * 2 socket, a bit different microcode:
>>
>> [   22.947525] smp: Brought up 32 nodes, 512 CPUs
>>
>> * your CPU, one socket:
>>
>> [   26.830137] smp: Brought up 16 nodes, 255 CPUs
> 
> (Probably unrelated but...)
> What happened to number 256 ?

Quick guess, maybe iommu was off, will cap it to 255. IIRC...

-- 
Jens Axboe