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SubjectRe: [RFC/PATCH] Make printk work for really early debugging
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On Thu, 2006-05-18 at 18:00 +0200, Andi Kleen wrote:
> On Thursday 18 May 2006 17:41, Michael Ellerman wrote:
> > On Thu, 2006-05-18 at 15:55 +0200, Andi Kleen wrote:
> > > Michael Ellerman <michael@ellerman.id.au> writes:
> > >
> > > > Currently printk is no use for early debugging because it refuses to actually
> > > > print anything to the console unless cpu_online(smp_processor_id()) is true.
> > >
> > > On x86-64 this is simply solved by setting the boot processor online very early.
> >
> > Yeah, someone suggested that. Unfortunately it doesn't work, we actually
> > want to call printk before we even know which cpu we're on :D
>
> You mean smp_processor_id() returns a random value?
>
> Then your patch is broken too because iirc it tested smp_processor_id()
> before that other flag

No it returns 0, but that seems to be the result of good luck rather
than good management. I think I owe you a beer :)

cheers

--
Michael Ellerman
IBM OzLabs

wwweb: http://michael.ellerman.id.au
phone: +61 2 6212 1183 (tie line 70 21183)

We do not inherit the earth from our ancestors,
we borrow it from our children. - S.M.A.R.T Person
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