x86 APIC interrupts for UP i810 chipset?

[Steve Underwood]

Jeff Garzik wrote:

> In looking through the i810 docs, it appears to me that the chipset
> provides an APIC even for uniprocessor configurations.
>
> Two dumb questions:
> Are my eyes deceiving me?  :)
> And, does Linux take advantage of these extra i810 interrupts on UP
> automatically?

The APIC is actually nothing to do with multi-processor systems. The
association comes from the fact that few uniprocessor systems currently use
the feature, regardless of the OS they run. APIC is a core feature of
interrupts on Pentiums, and has been supported by motherboards, to varying
degrees, since the birth of PCI.

Interestingly, the 810 documents confirm the RNG feature (random number
generator) is based on a natural noise source (the issued was discussed here
a few months ago), but gives no indication how they avoid digital noise
corrupting its purity. It would be interesting to perform a thorough
statistical analysis on a variety of motherboards using it. It can only
generate about 500 bytes per second, so the analysis might be somewhat slow.

Steve



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