Date: Sun, 11 Jun 95 19:18:29 EDT From: evanc@synapse.net (Evan Champion) To: hackers@freebsd.org Subject: Problem with 2940 Message-ID: <199506112318.TAA17166@sentinel.synapse.net>
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System: P75 on SiS chipset, 32 MB RAM (both 60 ns), Seagate Hawk 2 GB
(SCSI), Toshiba 3401B external CD (SCSI), Adaptec 2940 and a Surecom
(NE2000-compatible) PCI ethernet.
OS: FreeBSD 2.0.5-RELEASE running generic kernel (due to the problem I
describe below, you'll see how I was not able to create a new kernel
with less junk in it). Installed via Internet from
freefall.cdrom.com.
Problem: mild filesystem corruption. It appears that on write a bit
is being written improperly. If I take the case of the files in
/usr/include, there is in general one error every few lines of code in
those files that are affected (the corruptions are most apparent in
source code since the syntax checkers find them very quickly).
Viewing affected files shows the same corruption each time. Removing
the file and reextracting from the distribution may solve the problem,
but a new file that was just extracted will have a different
corruption. Again, viewing the new files will show the same new
corruptions each time.
The corruptions seem to be only 1 character at a time. Ones that I
see over and over in /usr/include are ")" turned to "(", "_" turned to
"^" and "*" turned to "+".
This difference will become much more apparent if I write out the
ASCII values for each (r = real value, c = corrupted value):
character value (octal) value (binary)
r ) 051 00101001
c ( 050 00101000
r _ 137 01011111
c ^ 136 01011110
r * 052 00101010
c + 053 00101011
Note that each is only 1 bit off, either by adding 1 or subtracting 1
from the real value.
Both the internal and external SCSI bus are properly terminated and
we're using high quality cables. I lowered the transfer rate from 10
MB/s to 5 MB/s with no change. I suspect that the problem is with the
2940 or the driver for the 2940 because SCSI bus parity should detect
the single bit errors that I am experiencing.
I hope someone out there is having this problem to so I don't feel
that I'm going crazy :-) Any suggestions as to what to look for and
change would be very appreciated.
Evan
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