Re: [RFC/PATCH] Make printk work for really early debugging

From: Michael Ellerman
Date: Mon May 22 2006 - 02:57:12 EST

On Thu, 2006-05-18 at 15:55 +0200, Andi Kleen wrote:
> Michael Ellerman <michael@xxxxxxxxxxxxxx> 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.

I had a closer look at this, and we could actually fudge it so that
cpu_online() is true in our early boot code, even though we don't know
what cpu we're on.

But that kind of begs the question, what does "cpu_online(x)" actually
mean? If it doesn't mean percpu data is allocated, what does it mean?


Michael Ellerman
IBM OzLabs

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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