Subject: Re: PWS PCI Slots
To: None <>
From: Ray Phillips <>
List: port-alpha
Date: 03/29/2003 11:45:33
>  > Could someone explain about the two long (64-bit?) PCI slots in the
>  > PWS, please?  I mean what's special about them...
>The Pyxis bug.  PCI DMA transfers that cross page boundaries are broken in the
>earlier Pyxis hardware, found on Miatas.

I suppose the faulty IC is on the the main logic board (the one the 
21164 CPU is on) rather than the lower one containing the ISA and PCI 

The boot probing messages at boot say

cia0 at mainbus0: DECchip 2117x Core Logic Chipset (Pyxis), pass 1
cia0: extended capabilities: 1<BWEN>
cia0: using BWX for PCI config access
cia0: WARNING: Pyxis pass 1 DMA bug; no bets...

However, I couldn't find an IC labelled something like 2117 or which 
had Pyxis on it.

Some time ago I saw a PWS main logic board for sale on ebay and was 
wondering if using it would have removed the problem.  It had USB 
ports so was more recent than mine.  Does that mean it was from a GL 
version PWS and would definitely not have this type of faulty chip?

Would any main logic board with USB ports be able to use a 600 MHz 
CPU?  If so, I guess it's just a matter of setting the DIP switch 
correctly--what are the right switch positions?

By the way, could you explain the memory values printed at boot time:

NetBSD 1.6Q (GENERIC) #0: Sun Mar 23 09:34:37 EST 2003
Digital Personal WorkStation 500au, 500MHz, s/n
8192 byte page size, 1 processor.
total memory = 256 MB
(1896 KB reserved for PROM, 254 MB used by NetBSD)
avail memory = 229 MB
using 1639 buffers containing 13112 KB of memory

I feel sure I should know what page size means, something to do with 
virtual memory, yes?

I couldn't figure out where the 229 MB of available memory value 
comes from; and the 1639 8 K  buffers--what are they used for?