Re: SMP speed on 6x86 UPt

Alan Cox (alan@lxorguk.ukuu.org.uk)
Fri, 20 Mar 1998 23:04:39 +0000 (GMT)


> > One problem - the code you are looking at should only be getting executed
> > on the real mode boot entry of the second or later _intel_ processor,
> > so Im baffled how it could be involved
>
> Why that? It's the normal way every the CPU starts to boot the kernel.
> Do other processors than second and later _intel_ processors have null
> in %bx for some reason ?

Ok the intel stuff has to boot the other CPU's in real mode (no I dont know
why intel did this either). We do a real mode start up in low memory using
the base of that CPU's kernel stack and jump into protected mode and to
the kernel entry code. the lock variable is used to detected 2nd or later
CPUs (bad things occur if CPU#2 also clears the BSS for example..)

> > Do nops to the same size as the jmp you added do anything.
>
> Sorry, I don't understand what you want to tell me here. I'd like to have an
> official SMP kernel running on my UP 6x86, that's why I try to find a real
> solution for this.

Im wondering if its something else like alignments

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