Re: [PARPORT] Re: Attention anyone using the pt driver

From: J. Scott Berg (
Date: Fri Jun 15 2001 - 00:01:05 EDT

  • Next message: Russel Ingram: "Re: [PARPORT] Re: Attention anyone using the pt driver"

    On Thu, 14 Jun 2001, Russel Ingram wrote:

    > On Thu, 14 Jun 2001, Russel Ingram wrote:
    > > I have added some extra functionality to the pt driver and am looking for
    > > people to test it. The attached patch will add the following magnetic
    > > tape ops to the driver:
    > >
    > > MTRETEN -- retention the tape
    > > MTLOAD -- load the tape
    > > MTUNLOAD -- unload the tape
    > > MTERASE -- erase the tape
    > > MTWEOF -- write end of file marker

    Ah, MTWEOF. I messed with this a while back and kept intending to get
    back to this but never did. Filemarks are sufficiently tricky that
    when I last messed with them (2.2.8?) the SCSI and IDE tape drivers
    did different things. I got confused and never got around to
    resolving the confusion. The tricky part is that a write operation
    followed by most any other operation really needs a filemark to be
    written. I believe the problem was whether a write operation followed
    by MTWEOF wrote one or two filemarks. Or something like that.
    Anyhow, the difference revolved around whether one or two filemarks
    got written (in the QIC-157 sense). And then the behavior of MTFSF
    and MTBSF, including which side of the filemark you ended up on, and
    whether one filemark was really two QIC-157 marks.

    Anyhow, you can tell that 1) the memories are fuzzy, and 2) I'm a bit
    confused. We (someone?) should probably figure out/decide what the
    "right thing" to do is and try to make all the tape drivers do the
    same thing, so that backup software writing a TR-4 tape on a SCSI
    drive can read it back transparently on a parallel port drive.

                                    -Scott Berg

    J. Scott Berg                 
    12 ROLLING HILLS DR                     (631) 924-8613
    RIDGE NY  11961

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