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

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.

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 ?

Tim