This document explains how to resolve bus error panics on a PCI system 
where the PCI slots are controlled by the PSYCHO(+) chipset. The following 
systems are included E250, E450, systems that have an U60 system board 
(U60, 220R and Netra t 1120/1125) and systems that use an U80 system board 
(U80, E420R and Netra t 1400/1405). 

The panic string in /var/adm/messages should look like this one:

WARNING: pcipsy-2: PCI fault log start:
PCI SERR
bytemask=0
WARNING: pcipsy-2: PCI primary error (0):
WARNING: pcipsy-2: PCI secondary error (0):
WARNING: pcipsy-2: PBM AFAR 0.00000000:    
WARNING: pcipsy-2: PCI config space error status (c280):
detected parity error.
signalled system error.
pcipsy-2: PCI fault log end.

panic[cpu1]/thread=2a10001fd40:
pcipsy-2: PCI bus 3 error(s)!
      
If the system is based on an U80 system board then check bug id 4339479,
which is a duplicate of bug id 4342026.                        

panic[cpu1]/thread=2a10001fd40: pcipsy-2: PCI bus 3 error(s)!

This E450 paniced due to a parity bus error on pcipsy-2.
pcipsy-2 refers to the instance 2 of the PCI Psycho driver.

Look into the /etc/path_to_inst file to find the physical path for the 
pcipsy-2 instance.

"/pci@4,4000" 2 "pcipsy"
    ^^^^^^    ^    
path___|      |__Instance

Now, you need to refer to the PCI slot numbering of the system board to 
know which PCI slots are using the same physical path.  

E250
pci@1f,2000/*@1,*	Slot 3
pci@1f,4000/*@2,*	Slot 2	
pci@1f,4000/*@4,*	Slot 1
pci@1f,4000/*@5,*	Slot 0

E450pci@1f,4000/*@4,* 	Slot 10
pci@4,4000/*@2,* 	Slot 9
pci@4,4000/*@3,* 	Slot 8
pci@4,4000/*@4,* 	Slot 7
pci@4,2000/*@1,* 	Slot 6
pci@1f,2000/*@1,* 	Slot 5
pci@6,2000/*@1,* 	Slot 4
pci@6,4000/*@2,* 	Slot 3
pci@6,4000/*@3,* 	Slot 2
pci@6,4000/*@4,*	Slot 1 

U60 based 
pci@1f,2000/*@1,* 	Slot 1
pci@1f,4000/*@2,* 	Slot 2
pci@1f,4000/*@4,* 	Slot 3
pci@1f,4000/*@5,*	Slot 4

U80 based
pci@1f,4000/*@5,*	Slot 4
pci@1f,4000/*@2,*	Slot 3
pci@1f,4000/*@4,*	Slot 2
pci@1f,2000/*@1,*	Slot 1                        

In our case (E450), the physical path "/pci@4,4000" corresponds to the PCI 
slots 7, 8 and 9. It is consistent with the panic string "PCI bus 3 error(s)."

Now, you can either look at the prtdiag -v output or the path_to_inst file to 
determine which PCI slots are populated. 

From the prtdiag output:
SYS   PCI    33     7   pci1044,a501
SYS   PCI    33     9   fibre-channel 

From the /etc/path_to_inst file:
"/pci@4,4000/fibre-channel@2" 1 "fca-pci"       >>> 3rd party PCI card
"/pci@4,4000/pci@4" 2 "pci_pci"			>>> DPT Raid HW controller (p/n 375-0078)
	"/pci@4,4000/pci@4/scsis@4" 0 "dpti2o"
	"/pci@4,4000/pci@4/scsis@4/mscsi@2,0" 2 "mscsi"

Slots 7 and 9 are populated. It is not possible to tell which card may be the  
cause of the panic, so it is recommended to replace both cards.
 
If the problem is persistent after replacing the cards then you should consider 
replacing the system board.