Re: Serverworks OSB4 in impossible state

From: Martin Wilck (
Date: Tue Jun 11 2002 - 06:25:25 EST

[Alan, I am cc'ing you on this because I read elsewhere that you want to be forwarded to you, and that address still

I have tried the following:

- comment out the code that stalls the machine when the condition in
  question is encountered.
- run dd over a couple of good blocks on the CD.
- run dd over the corrupted blocks. This leads now to very similar
  errors as in the PIO case.
- reenable DMA with hdparm, because it is automatically disabled by the
  ide-cd driver if an error occurs (why that? the error has nothing to
  do with DMA here).
- repeat the first dd command on the good blocks and compare the

The results are identical, thus I cannot verify the "4 byte shift" Alan
has been talking about. Of course this is a CD-ROM only scenario, thus
I can't tell anything about hard disks.

Is it possible that the 4-byte shift occurs only with some particular
(older?) version of the chipset?

In any case, the condition that usually causes Linux to stall is
indeed a perfectly valid condition for DMA when the device transfers
less data than it's supposed to. I doubt that hanging the system
without more detailed checks is the right measure to take there.


Martin Wilck                Phone: +49 5251 8 15113
Fujitsu Siemens Computers   Fax:   +49 5251 8 20409
Heinz-Nixdorf-Ring 1
D-33106 Paderborn 

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