Messages in this thread | | | Date | Sun, 19 Dec 1999 18:36:25 -0500 | From | Doug Ledford <> | Subject | Re: Domain validation |
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Wakko Warner wrote: > > Why does linux (2.2.13) always perform domain validation every time I change > cd's? Even in the changer I have (which 1 cd was mounted) mounting another > cd caused this. The last time it did this the scsi bus froze.
The aic7xxx driver is doing it because it's getting a CHECK_CONDITION return from the CD device. Since CHECK_CONDITION is the proper response in the case that parity errors cause an aborted transfer to the device, we have to accept it as a possible indicator that there might be transfer problems, so we then perform domain validation. Please note that domain validation in the aic7xxx driver uses the same code as SDTR/WDTR negotiations, so I seriously doubt it locked up your system, it just happened to be the last message displayed. Also note that most devices only rarely return CHECK_CONDITION responses, but CDs do so in order to signal a disk change, so yes, you will get a domain validation with each CD change. You'll also get them with each reset, and several other conditions, but in general, they should be rare.
I could actually poke around in the sense data returned after a check condition and see if we actually need to perform a domain validation, but that would just be another case of the low level driver doing something it shouldn't be doing at all (parsing generic error returns in sense data and deciding what to do next, this stuff is all generic SCSI protocol stuff and shouldn't be in the low level driver IMO).
-- Doug Ledford <dledford@redhat.com> Opinions expressed are my own, but they should be everybody's.
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