[2142] in Release_Engineering
VS3100 ethernet problem
daemon@ATHENA.MIT.EDU (Mark Rosenstein)
Thu Jan 11 16:27:13 1990
Date: Thu, 11 Jan 90 16:26:36 -0500
From: Mark Rosenstein <mar@MIT.EDU>
To: treese@MIT.EDU, rel-eng@MIT.EDU
Cc: mar@MIT.EDU, towle@MIT.EDU, jfc@MIT.EDU
Here's a summary of the problem we're having:
Our kernel & network bootstrap work fine on VS3100 model 30's with
8Meg and RZ23 disk. We're having trouble with this software on VS3100
model 40's with 20Meg and RZ55 disks.
The kernel boots, but the first ifconfig fails to bring up the
network. If we ifconfig the network back down and then up again, it
mostly works, but sometimes under load goes deaf to the net for 10
seconds at a time, making the machine unusable. The network bootstrap
code claims it initialized the network, but always gets transmit
timeouts sending packets.
I've verified that the problem is memory-related and not a disk
problem by pulling the disk controller and running the machine
diskless; we still see the same problem. The machine fails to boot
with only the 4Meg of memory on the motherboard. With a 4Meg add-on
card (8 Meg total), the machine will netboot, but the disk controller
is never recognized so I can't run real Unix. I'm told that there are
no jumpers to change when we change the amount of memory.
One thing we have discovered is that the LANCE chip (ethernet
controller) can only address 24 bits of memory, so it can only DMA to
the first 16Meg of memory. However, we've verified that the software
isn't trying to use the top 4Meg at the point where we're failing.
DEC customer support hasn't been very useful. I'm trying to track
down a technical manual on that CPU board to see if that helps. If I
can get ahold of an Ultrix distribution, I'll try that too.
Further suggestions welcome.
-Mark
