Re: Gigabyte 6VXDC7 mobo (Via 694X chipset) SMP instability

[Earle Nietzel <earle.nietzel@rhinobox.org>]

Tim Day wrote:
> On Wed, 2005-05-04 at 22:23 -0400, Earle Nietzel wrote:
> 
>>Tim Day wrote:
>>
>>>I have a machine with a Gigabyte 6VXDC7 mobo (Via 694X chipset) with a
>>>pair of 933MHz P3s and a couple of GB of RAM.  I run Debian Sarge's
>>>stock -686-smp kernels (2.4 series or more recently 2.6.8).
>>>
>>>With a "nosmp" boot option (or using uniprocessor kernels) the box is
>>>rock solid.  But when I run in SMP mode it generates sporadic
>>>  "APIC error on CPUx: 0y(0z)"
>>>type messages, generally in pairs, every few minutes (or several per
>>>minute with the 2.6.8 kernel without a "noapic" boot option).
>>>Eventually the machine invariably locks up hard with no warning after an
>>>uptime of on the order of a few minutes or a few days (depending on
>>>kernel version, boot options, load and luck).  I've tried just about
>>>every possible combination of BIOS settings and boot options, memchecked
>>>the RAM, rearranged PCI cards and upgraded the PSU.  Nothing seems to
>>>help; the only way to get complete stability seems to be "nosmp" or a
>>>non-SMP kernel.
>>
>>Have you tried using "noapic"?
> 
> 
> Oh yes.
> It has the expected effect on /proc/interrupts:
> IO-APIC-edge/-level interrupts spread over both CPUs change
> into XT-PIC interrupts on CPU0 only.
> Nevertheless, the steady stream of "APIC error" kernel messages remains.

I remember the ABIT BP6 motherboards having a similar problem but it was 
because one of the cpu's had a voltage difference large enough to cause 
this type of error (though there were no stability issues).

> 
> Is it possible to build an SMP kernel with the APIC hardware completely
> ignored/disabled (to an even greater extent than with "noapic"), or is
> the APIC hardware needed for some crucial aspect of inter-CPU
> communication ?

I pretty sure that is not possible. The "noapic" option often solved 
problems on some buggy motherboards.

There does come to mind one other thing you might try and that is in 
your BIOS if you can change the SMP compatibility between "MP 1.1" or 
"MP 1.4". If you have this option try it out.

> 
> Tim
> 
> 
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