johnk@grebyn.COM (John Kennedy) (05/08/89)
I've been experiencing a bizarre problem with a Sys V/AT that
is no longer able to read or write floppies. Everything works
fine under MS-DOS, but not under unix. This is starting to become
a serious problem, as I am not able to back up the system.
Just wondering if anyone else has had any similar problems.
Hardware is:
16-Mhz 286, 2 meg 80 ns memory.
40 MB ST-251-1 hard drive
1.2 MB floppy drive
360 KB floppy drive
misc serial ports, monitor, etc.
Software is:
Sys V/AT, ver 2.3 installed on hard drive.
- or -
Sys V/AT, ver 2.3 booted from uport boot floppy.
- or -
Sys V/AT, ver 2.4 booted from uport boot floppy.
Symptoms are (from hard disk):
1 - Format (floppies) works with no displayed errors. Does this mean that
it was successful or that errors aren't reported?
2 - Any read or write (cpio, dd) yields I/O errors.
3 - Both 1.2 MB and 360 KB floppies get the errors.
(from boot floppy)
1 - Booting the uport boot floppy, either sys VAT 2.3 or 2.4 yields
"panic - cannot mount root".
I have ruled out any patches to the kernel for serial ports, interrupts,
etc, as a problem exists in booting the distribution floppies.
I have tried removing all hardware except the disk controllers and
CRT controllers, and the problems persist.
At this point, the disk drives and controller cards have been replaced. I am
beginning to suspect something on the mother board, having to do with
DMA transfers, or some other feature that uport utilizes, that DOS doesn't.
Am looking for any insights as to what features of the hardware uport
utilizes, that DOS doesn't.
The only other next step for me is to replace the mother board, but
I would really like to what's going on.
Thanks in advance for any insights,
John
--
John Kennedy | Second Source, Inc.
johnk@opel.UUCP | Annapolis, MDplocher%sally@Sun.COM (John Plocher) (05/09/89)
In article <11944@grebyn.COM> johnk@opel.UUCP (John Kennedy) writes: >I've been experiencing a bizarre problem with a Sys V/AT that >is no longer able to read or write floppies. Everything works >fine under MS-DOS, but not under unix. This is starting to become > >At this point, the disk drives and controller cards have been replaced. I am >beginning to suspect something on the mother board, having to do with >DMA transfers, or some other feature that uport utilizes, that DOS doesn't. I think you hit it on the head here. Microport uses DMA for the floppy device, DOS does not. One way to test this out is try (under DOS) the fastback install program. It tests the DMA chips under a simulated load and will tell you if the DMA controller is bad. If it is, hope and pray it is socketted on the motherboard (and not soldered :-). Replacing it should solve the problem (and should cost less than $15.00 - much less than that new 386 motherboard you were hoping you had an excude to buy :-) -John Plocher
rcd@ico.ISC.COM (Dick Dunn) (05/09/89)
In article <11944@grebyn.COM>, johnk@grebyn.COM (John Kennedy) writes: > I've been experiencing a bizarre problem with a Sys V/AT that > is no longer able to read or write floppies. Everything works > fine under MS-DOS, but not under unix... ... > Software is: > Sys V/AT, ver 2.3 installed on hard drive. (etc.) I've seen bizarre problems under V/AT 2.2 on my machine at home. I had pretty much decided that Microport was programming the floppy controller wrong somehow, and it had something to do with formatting, because I could use the machine's drive to format/read/write floppies under MS/DOS and another UNIX, and to move floppies to/from the machine, but had a consistent class of troubles with Microport. Specifically, >>I could only read a floppy under Microport if it had been formatted under Microport.<< All other non-Microport combinations worked. One of the notable failures was to format and write a floppy under MS/DOS, then be unable to read it under Microport on the same machine! I also found that I would get repeatable errors on some floppies--as if they were solidly bad--under Microport, yet I could use the floppies with nary a complaint under other systems on the same machine. I'm at a loss to explain this sort of behavior *except* as a driver problem. It's as if the driver is doing something to get out in the margins. > 1 - Format (floppies) works with no displayed errors. Does this mean that > it was successful or that errors aren't reported? There are very few things that cause a format to report an error. In par- ticular, there's no verification that the formatting actually happened. > 3 - Both 1.2 MB and 360 KB floppies get the errors. Beware that you cannot dependably *write* a 360 Kb floppy in a 1.2 Mb drive. That's a matter of hardware; it's not *supposed* to work even though it sometimes does. You can read them, though. If you've got a 1.2 Mb drive, you should be using HD floppies (*not* DD), formatting them in high density (80 tracks * 2 sides), and writing in high density. > 1 - Booting the uport boot floppy, either sys VAT 2.3 or 2.4 yields > "panic - cannot mount root". This (and some other comments) says that you've got hardware problems. Microport's problems with floppies may be making it worse, but there's something else going on. -- Dick Dunn UUCP: {ncar,nbires}!ico!rcd (303)449-2870 ...Relax...don't worry...have a homebrew.
buck@siswat.UUCP (A. Lester Buck) (05/13/89)
In article <103727@sun.Eng.Sun.COM>, plocher%sally@Sun.COM (John Plocher) writes: >>beginning to suspect something on the mother board, having to do with >>DMA transfers, or some other feature that uport utilizes, that DOS doesn't. >I think you hit it on the head here. Microport uses DMA for the floppy device, >DOS does not. DOS *does* use the DMA hardware for the floppy transfers. Check the BIOS listings in the Tech Reference manuals. >One way to test this out is try (under DOS) the fastback install >program. It tests the DMA chips under a simulated load and will tell you if >the DMA controller is bad. If it is, hope and pray it is socketted on the I have no direct experience with Fastback, but I have read that it is only checking that your DMA chip can support two simultaneous DMA transfers (i.e., two DMA channels active at once). If the DMA chips did not support a single DMA transfer, you would not be able to boot from the floppy. -- A. Lester Buck ...!texbell!moray!siswat!buck