From mboxrd@z Thu Jan  1 00:00:00 1970
From: Arun Sharma <arun.sharma@intel.com>
Subject: Re: Fix for 'acpi=off'
Date: Thu, 05 May 2005 16:09:49 -0700
Message-ID: <427AA7BD.2080505@intel.com>
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To: "Puthiyaparambil, Aravindh" <aravindh.puthiyaparambil@unisys.com>
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Puthiyaparambil, Aravindh wrote:
> I tried the acpi=off on my 2-by x86_64 box running 32-bit SLES9.
> Everything seems to work just fine except for a couple of pfn and page
> fault non-fatal errors.
> 
> But with acpi=ht, Dom0 hangs while trying to bring up the SCSI devices.
> I have included debug output for both cases.
> 

I think this is the issue you're running into:

> SMP mptable: no processors registered!
> BIOS bug, MP table errors detected!...
> ... disabling SMP support. (tell your hw vendor)

With acpi=off acpi_lapic is non-zero so this code works:

    /* ACPI may have already provided this data */
    if (!acpi_lapic)
            MP_processor_info(m);

But with acpi=ht, MP table processor info is ignored. I worked around it
by ignoring the processor entries in the MP table always and setting
num_processors=1.

	-Arun