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Date: Wed, 18 Jun 2008 20:33:35 -0400 (EDT)
From: Len Brown <lenb@kernel.org>
Subject: Re: [PATCH] x86: update mptable v7
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To: Yinghai Lu <yhlu.kernel@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>, Thomas Gleixner <tglx@linutronix.de>,
       "H. Peter Anvin" <hpa@zytor.com>,
       Andrew Morton <akpm@linux-foundation.org>,
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On Wed, 18 Jun 2008, Yinghai Lu wrote:

> On Wed, Jun 18, 2008 at 3:18 PM, Len Brown <lenb@kernel.org> wrote:
> >
> >
> > On Sun, 1 Jun 2008, Yinghai Lu wrote:
> >
> >>
> >> make mptable to be consistent to acpi routing, so we could
> >> 1. kexec kernel with acpi=off
> >> 2. workaround BIOS that acpi routing is working, but mptable is not right.
> >>    so can use kernel/kexec to start other os that doesn't have good acpi support
> >
> > Is this an effort to boot an ACPI-mode kernel,
> > and then kexec a non-ACPI kernel?
> 
> Yes,

Why is this feature needed?
There are a number of ways that the resulting kernel may fail,
all platform specific.

> >
> > Doing so could confuse the heck out of the platform firmware,
> > which will think that an ACPI-mode kernel is still running.
> >
> > Note that it is a historic artifact, now considered a bug,
> > that ACPI uses the MPS code.  We should be divorcing these
> > two bodies of code rather than mixing them further.
> 
> how about adding config option to not compile mptable related info?

That's the idea.
CONFIG_MPS=n CONFIG_ACPI=y should build and run on
every PC built in this century.

This was prototyped a long while back, but the
tree has churned so much since then the old
prototype is worthless.

-Len