I've inherited an old IBM Netfinity 5600 (it's a model # 8664-11y) that has
2 PIII, 533MHz procs and an Adaptec U2W SCSI adapter:

  cpu0 at mainbus0: (uniprocessor)
  cpu0: Intel Pentium III (686-class), 533.11 MHz, id 0x681
  cpu0: features 387fbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR>
  cpu0: features 387fbff<PGE,MCA,CMOV,PAT,PSE36,PN,MMX>
  cpu0: features 387fbff<FXSR,SSE>
  cpu0: I-cache 16 KB 32b/line 4-way, D-cache 16 KB 32b/line 4-way
  cpu0: L2 cache 256 KB 32b/line 8-way
  cpu0: ITLB 32 4 KB entries 4-way, 2 4 MB entries fully associative
  cpu0: DTLB 64 4 KB entries 4-way, 8 4 MB entries 4-way
  cpu0: serial number 0000-0681-0002-EDD7-59A4-9AB1
  cpu0: 8 page colors

  ahc0 at pci1 dev 3 function 0: Adaptec aic7896/97 Ultra2 SCSI adapter
  ahc0: interrupting at irq 10
  ahc0: aic7896/97: Ultra2 Wide Channel A, SCSI Id=7, 32/253 SCBs
  scsibus0 at ahc0: 16 targets, 8 luns per target
  ahc1 at pci1 dev 3 function 1: Adaptec aic7896/97 Ultra2 SCSI adapter
  ahc1: interrupting at irq 10
  ahc1: aic7896/97: Ultra2 Wide Channel B, SCSI Id=7, 32/253 SCBs
  scsibus1 at ahc1: 16 targets, 8 luns per target

It's also got a 6 18.0GB disks on the SCSI bus that I'm using
for a PostgreSQL database.

This whole things works pretty well, but *only* when configured as a
uniprocessor machine.  If I turn on SMP, the SCSI adapter freaks out
when it's probed with messages almost identical to these:

  http://www.mcs.vuw.ac.nz/~duncan/ahc-dump.txt

Basically, the only difference of importance is at the bottom of the
page referred to by that URL.  Where it says:

  st0(ahc0:0:6:0): ahc0: no longer in timeout, status = 0

I'm seeing

  probe(ahc0:0:0:0): ahc0: no longer in timeout, status = 0


I've checked on IBM's support page and can't find a newer version of the
BIOS for this adapter.  Adaptec does have newer BIOSs:

  http://www.adaptec.com/worldwide/support/driverdetail.jsp?sess=no&language=English+US&cat=/Product/AHA-2940U2W&filekey=2940u2w_bios_v2572.exe

But they specifically state that this might break OEM versions and I'd
rather not risk blowing out the SCSI adapter on this machine.


Can anyone shed any light on what's going on here?  Is this a firmware bug?
Bad interaction between ahc0 and SMP?  Something else?


Thanks,

Paul
-- 
Paul Dokas                                            dokas@cs.umn.edu
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Don Juan Matus:  "an enigma wrapped in mystery wrapped in a tortilla."