Re: [PATCH] APIC physical broadcast for i82489DX

[Maciej W. Rozycki]

On Thu, 7 Oct 2004, William Lee Irwin III wrote:

> > @@ -91,7 +91,7 @@
> >  	unsigned int lvr, version;
> >  	lvr = apic_read(APIC_LVR);
> >  	version = GET_APIC_VERSION(lvr);
> > -	if (version >= 0x14)
> > +	if (!APIC_INTEGRATED(version) || version >= 0x14)
> >  		return 0xff;
> >  	else
> >  		return 0xf;
> 
> This is the same as version <= 0xf || version >= 0x14; I'm rather

 I suppose defining a macro called something like APIC_XAPIC(x) to (x >= 
0x14) might actually have some sense, although unlike with the i82489DX, 
there is no promise for this to be always true.

> suspicious, as the docs have long since been purged, making this

 AFAIK i82489DX documents were never available online and I suppose they
might have never existed in a PDF form.  You could have ordered hardcopies
in mid 90's.

> hopeless for anyone without archives (or a good memory) dating back to
> that time to check. All that's really needed is citing the version that
> comes out of the version register and checking other APIC
> implementations to verify they don't have versions tripping this check,

 The APIC_INTEGRATED() macro reflects the range reserved for the i82489DX.  
Both "Multiprocessor Specification" and "IA-32 Intel Architecture Software
Developer's Manual, Vol.3" which are available online specify it clearly
and explicitly.  AFAIK, there is no integrated APIC implementation that
would violate it (unlike with I/O APICs), so what's the problem?  If a 
buggy chip appears, we can revisit this assumption.

> the latter of which is feasible for those relying on still-extant
> documentation. Better yet would be dredging up the docs... So, what is
> the range of the version numbers reported by i82489DX's?

 The i82489DX datasheet documents 0x01 for the chip and the
implementations I've encountered so far agree.

  Maciej
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