Re: [PATCH] x86: do_boot_cpu - add check if we have ESR register

[Ingo Molnar <mingo@elte.hu>]

* Yinghai Lu <yhlu.kernel@gmail.com> wrote:

> > Actually it's resend of the patch. On previous attempt Yinghai was 
> > proposed to choose:
> >
> >> one apic_version or boot_cpu_apic_version could be enough
> >
> > but I think it should be different patch which does cleaning up 
> > variables usage. So for now I think _this_ patch is enough since 
> > idea is to prevent of touching nonexistant register rather code 
> > cleaning (whci could be done later).
> 
> do we have systems that have mixed cpu supported with different apic 
> version?

i dont think that ever happened in the past. Vendors have trouble 
keeping same-cpu type systems going ;-)

OTOH, if it's simple to have multi-version support then lets do that 
throughout. (although we certainly cannot test it. Perhaps we can 
provoke it artificially via a hack that artificially degrades one cpu's 
apic version or so.)

	Ingo