Re: Serverworks OSB4 in impossible state

[Martin Wilck <Martin.Wilck@Fujitsu-Siemens.com>]

[Alan, I am cc'ing you on this because I read elsewhere that you want 
osb4-bug@ide.cabal.tm to be forwarded to you, and that address still
bounces]. 

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
  results.

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
 
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