Re: [PARPORT] More HP-7200e problems :-(

From: Joerg Schilling (schilling@fokus.gmd.de)
Date: Wed Jan 10 2001 - 17:21:19 EST

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    >From twaugh@meme.surrey.redhat.com Wed Jan 10 20:46:22 2001

    >On Wed, Jan 10, 2001 at 07:23:21PM +0100, schilling@fokus.gmd.de wrote:

    >> If I understand you correctly: cdrecord only works with IDE-SCSI
    >> then you are fooled by the Linux binary incompatibility problem.
    >>=20
    >> did you compile cdrecord on the machine where you made the tests?
    >>=20
    >> BTW: cdrecord-1.10a11 tries to work around this particular problem.

    >I still haven't really seen an explanation of what the actual
    >_bug_ with this is. Does anyone actually know?

    libscg 'knows' the possible errno's from the sg driver.
    Under some strange circumstances, it seems that there are unexpected
    errno's. If libscg encounters such an unexpected errno it assumes
    that something really bad happened and scg_cmd() returns -1.
    The higher level SCSI trasnport exits if scg_cmd() returns -1.

    One thing that I added some weeks ago is to believe that ENOTTY
    is a known errno for some resons.

    THe background is that Linus drivers in general are not behaving correctly
    in returning EINVAL for an unknown ioctl() - the standard compliant
    errno would be ENOTTY. From the report I got some weeks ago, there
    has been ENOTTY retured. It is not clear whether this has been caused
    by a not loaded kernel module (*) or by some other strange effect.

    (*) It would be rally a good idea if Linux could load driver on demand
    as it is done on Solaris.

    /*--------------------------------------------------------------------------*/
    Final statement:

    if higher level code calls exit() before scanbus will touch the PP subsystem
    cdrecord cannot detect a PP drive.

    Another hint: cdrecord-1.8.1 is the first release of cdrecord that works
    on a system without SCSI & ATAPI (only PP present).

    I found/fixed the bug when I was alone with my notebook in NYC in feb. 2000
    when attending the Linux World Expo while trying to hack a bit in the
    hotel room ;-)

    Jörg

     EMail:joerg@schily.isdn.cs.tu-berlin.de (home) Jörg Schilling D-13353 Berlin
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