David.B.Stewart@fas.ri.cmu.edu (02/23/90)
Original-posting-by: David.B.Stewart@fas.ri.cmu.edu
Original-subject: SCSI Bus Errors
Reposted-by: emv@math.lsa.umich.edu (Edward Vielmetti)
Our SCSI controller interrupt handlers is detecting bus errors on our
system for unknown reason at arbitrary times when a M68020 coprocessor
board is in our system.
SYSTEM: Sun 3/160 w/ 4MBytes RAM, SunOS 4.0.3.
SCSI: Defined as following in the CONFIG file; it works fine as long as
the coprocessor board is not being used.
controller si0 at vme24d16 ? csr 0x200000 priority 2 vector siintr 0x40
disk sd0 at si0 drive 0 flags 0
disk sd1 at si0 drive 1 flags 0
tape st0 at si0 drive 32 flags 1
COPROCESSOR BOARD: It was originally at intr priority level 3, but I
thought that could be the problem, so I lowered it to the same intr level
priority. (Ideally I would like to keep my device at priority level 3).
device hxm0 at vme32d32 ? csr 0x40000000 priority 2 vector hxmintr 0x52
THE ERROR THAT KEEPS RECURRING IS THE FOLLOWING: When I get one, I get
dozens, and sometimes hundreds. Sometimes the system recovers, other
times I am forced to Abort the system and reboot, at which time my
filesystem is usually damaged to the point where I have to run fsck
manually.
siintr: bus error during dma
last phase= 0x0 (BUS FREE)
csr= 0x334f bcr= 42440 tcr= 0x4
cbsr= 0x60 (DATA OUT) cdr= 0x0 mr= 0x2 bsr= 0x10
target= 0, lun= 0 DMA addr= 0x5a00 count= 42496 (57344)
cdb= a 0 9c 6 70
PROBLEM:
The coprocessor is accessed through an mmap() driver. It's interrupt
handler only does a psignal().
Currently, the coprocessor board NEVER becomes bus master, with the
exception of generating the Level 2 (or 3) interrupt. One or more
processes on the Sun Workstation are reading/writing the memory and
registers of the coprocessor board, all of which are between 0x40000000
and 0x40400000 in A32D32 space. (4MBytes of memory) I have tried setting
the board to other random addresses, both in A32D32 and A42D32 space, but
to no avail.
The problem happens at random times; I could not pinpoint a certain event
that causes the error.
REQUEST:
Could someone with more information to the possible cause of the error
please send me email. I will summarize if I get any solutions.
Thanks a great deal,
David B. Stewart, Dept. of Elec. & Comp. Engr., and The Robotics Institute,
Carnegie Mellon University, email: stewart@faraday.ece.cmu.edu
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