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4. Intel architecture specific questions

4.1 Why it doesn't work on my machine?

  1. Can I use my Cyrix/AMD/non-Intel CPU in SMP?

    Short answer: no.

    Long answer: Intel claims ownership to the APIC SMP scheme, and unless a company licenses it from Intel they may not use it. There are currently no companies that have done so. (This of course can change in the future) FYI - Both Cyrix and AMD support the non-proprietary OpenPIC SMP standard but currently there are no motherboards that use it.

  2. Why doesn't my old Compaq work?

    Put it into MP1.1/1.4 compliant mode.

  3. Why doesnt my ALR work?

    From Robert Hyatt : ALR Revolution quad-6 seems quite safe, while some older revolution quad machines without P6 processors seem "iffy"...

  4. Why does SMP go so slowly? or Why does one CPU show a very low bogomips value while the first one is normal?

    From Alan Cox: If one of your CPU's is reporting a very low bogomips value the cache is not enabled on it. Your vendor probably provides a buggy BIOS. Get the patch to work around this or better yet send it back and buy a board from a competent supplier.

  5. I've heard IBM machines have problems

    Some IBM machines have the MP1.4 bios block in the EBDA, allowed but not supported by <2.1.80. Please update to the right kernel.

    There is an old 486SLC based IBM SMP box. Linux/SMP requires hardware FPU support.

  6. Is there any advantage of Intel MP 1.4 over 1.1 specification?

    Nope (according to Alan :) ), 1.4 is just a stricker specs of 1.1.

  7. Why does the clock drift so rapidly when I run linux SMP?

    This is known problem with IRQ handling and long kernel locks in the 2.0 series kernels. Consider upgrading to a later 2.1 kernel (not garenteed to work).

    From Jakob Oestergaard: Or, consider running xntpd. That should keep your clock right on time. (I think that I've heard that enabling RTC in the kernel also fixes the clock drift. It works for me! but I'm not sure whether that's general or I'm just being lucky)

  8. Why are my CPU's numbered 0 and 2 instead of 0 and 1 (or some other odd numbering)?

    The CPU number is assigned by the MB manufacturer and doesn't mean anything. Ignore it.

  9. My SMP system is locking up all the time. Black screen, nothing in the logs. Help!

    If you're running a 2.0 kernel, consider upgrading to later 2.0.32+ kernels or apply Leonard Zubkoff's deadlock patch. If you still have deadlocks, apply Ingo Molnar's deadlock detection patch and post the results (against your to linux-smp or linux-kernel. You might also consider running a 2.1 kernel.

4.2 Possible causes of crash

You'll find in this section some possible reasons for a crash of an SMP machine (credits are due to Jakob Oestergaard for this part). As far as I (david) know, theses problems are Intel specific.

Some hardware is also known to cause problems. This includes:

4.3 Motherboard specific information

Some more specific information can be found with the survey of SMP motherboards

Motherboards with known problems

Motherboards with no known problems

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