[CentOS] smp falls back to up mode on quad core

Wed May 28 15:09:41 UTC 2008
Julian Echave <julian.echave at gmail.com>

Solved it!
After quite a lot of messing around...
It turns out i was booting with the acpi=off option, but for the BIOS to see
the 4 processors acpi has to be on.
The problem was that with acpi=on, boot hangs, unless pci=nommconf is added
to the boot options.

To summarize,

I now boot using the options

acpi = on pci=nommconf



On Tue, May 27, 2008 at 6:29 PM, MHR <mhullrich at gmail.com> wrote:

> On Tue, May 27, 2008 at 1:41 PM, John R Pierce <pierce at hogranch.com>
> wrote:
> > Julian Echave wrote:
> >>
> >> Sure, find below, I add other stuff as well. Note that there is some bug
> >> in the Bios. This does not prevent Centos to boot, and, since Windows
> sees
> >> all four processors, I reckon it shouldn't be the problem...?
> >
> >
> > yeah, looks like its probably broken ACPI data in the BIOS.  see if the
> > mainboard or system vendor has a BIOS update to fix this.   just because
> > operating system "X" works, doesn't mean its 'right'.
> >
> You can try adding 'noacpi' to your boot string in your grub.conf file
> and see if that helps.
> I have an AMD Athlon 64 x2 on an ECS mobo that is known to have a
> problem with acpi.  If I try to run without the noacpi switch, it runs
> very poorly and crashes or halts within minutes of booting, if it
> boots at all.  With the flag, it runs smooth as silk.
> mhr
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