Re: SMP

[Oleg Krivosheev <kriol@bpmail.fnal.gov>]

Hi,

On Thu, 17 Feb 2000, Phil Brutsche wrote:

> A long time ago, in a galaxy far, far way, someone said...
> 
> > On Wed, 16 Feb 2000, aphro wrote:
> > 
> > > you sure that MB supports dual processors? it seems as if linux doesn't
> > > say its a SMP capable MB at all.
> > 
> > Well, the machine (AcerAltos) has two slots for CPU daughterboards.
> >  
> > > can linux run on SMP 486s ? never heard of anyone who ever ran a dual cpu
> > > 486, although ive heard of their existance..
> > 
> > What's so "special" about 486s so that they couldn't run in parallel?
> 
> In order to run parallel, processors need special wiring and circuitry to
> handle the 'bus protocol' for synchronizing bus accesses and what not.  
> Not all processors have that; it's possible that 486s don't.  That would
> explain why Linux doesn't see the motherboard as dual capable - the
> necessary circuitry isn't there.  The necessary circuitry would then be
> provided by the second CPU card.  This is why AMDs K6, K6-II, and K6-III
> (iirc[1]) don't do SMP - they lack the necessary circuitry.
> 
> Another reason why Linux doesn't see the computer as dual capable just
> dawned on me: in pre-Pentium systems (and even some early Pentium systems)
> there was no unified 'standard' method for the operating system to detect
> and initialize the additional CPUs.

i believe Intel MPI specs predates Pentium and were used for 486 boards. 
Therefore Linux should work on 486 SMP systems


OK