OSDev.org

I was thinking of the APIC implementation, and then I thought: isn't the i8259 PIC on the CPU die on modern processors (just like the APIC) ?
If it's the case, how could there be a bug in the PIC ? Intel/ADM would reuse their old design for this part of the dies, and that's it (so old circuitry which is well tested, no bug in sight)...

Magyar57 wrote: ↑Tue Mar 25, 2025 5:58 pmisn't the i8259 PIC on the CPU die on modern processors (just like the APIC) ?

It might be. You can try checking your CPU's datasheet.

Magyar57 wrote: ↑Tue Mar 25, 2025 5:58 pmIf it's the case, how could there be a bug in the PIC ?

Who would notice a bug in the PIC? Modern OSes don't use it, they have APIC.

Octocontrabass wrote: ↑Tue Mar 25, 2025 6:31 pm It might be. You can try checking your CPU's datasheet.

I've tried numerous times, but every time I just end up with the poor Intel or AMD marketing pdf with stuff like number of cores, frequency and that's it. Do you know where to find it ? (say, for the r7 7840hs)

Octocontrabass wrote: ↑Tue Mar 25, 2025 6:31 pm Who would notice a bug in the PIC? Modern OSes don't use it, they have APIC.

What I meant is, it has been well used and tested back in the days, and now since it's not used anymore (but for backward compatibility), they have no reasons to change the circuit and therefore introduce bugs: "if it works, don't touch it"

Magyar57 wrote: ↑Wed Mar 26, 2025 4:47 am What I meant is, it has been well used and tested back in the days, and now since it's not used anymore (but for backward compatibility), they have no reasons to change the circuit and therefore introduce bugs: "if it works, don't touch it"

Possibly, but the system design might have introduced a regression somewhere, or maybe the thing is wired up wrong internally, and that wouldn't be noticed.

Magyar57 wrote: ↑Wed Mar 26, 2025 4:47 am(say, for the r7 7840hs)

Processor Programming Reference (PPR) for AMD Family 19h Model 70h, Revision A0 Processors

Sorry I missed you message, thank you ! How did you find this ?
Btw I'm working on the APIC, but I need to setup paging first to read some memory address, so it will take a while x)

Magyar57 wrote: ↑Fri Apr 04, 2025 3:08 amHow did you find this ?

I searched the AMD documentation hub for your CPU's family and model.