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    SubjectRe: Linux v2.5.43

    On Wed, 16 Oct 2002, Shawn wrote:
    > On 10/16, Bill Davidsen said something like:
    > > On Tue, 15 Oct 2002, Linus Torvalds wrote:
    > > > A huge merging frenzy for the feature freeze, although I also spent a few
    > > > days getting rid of the need for ide-scsi.c and the SCSI layer to burn
    > > > CD-ROM's with the IDE driver (it still needs an update to cdrecord, I sent
    > > > those off to the maintainer).
    > >
    > > I hope you haven't broken running WITH ide-scsi, because most people still
    > > run 2.4 kernels in real life and only test 2.5 because someone has to do
    > > it. Reconfiguring the system to use ide-scsi or not is just one more PITA
    > > thing which needs to be done, or more likely forgotten, with every new
    > > kernel.
    >
    > Honestly, I think it's ok to bust the old stuff if needed. This is
    > simply my opinion from a user standpoint.

    Anyway, ide-scsi should work as well as it ever did, which is not to say
    too well. It's just that the IDE native implementation is cleaner and
    simpler, and a _hell_ of a lot easier to use.

    The scsi-generic layer is a total nightmare. If you want to write to the
    device that is /dev/scd0, you can't just use /dev/scd0, you have to use
    the right /dev/sgX, and the X depends on how many disks etc you have in
    the system and where your controller is. The amount of crap you have to do
    with things like "cdrecord -scanbus" to just figure out what the right
    device is is just ludicrous.

    With the native IDE setup, if your CD is /dev/hdc, then that's what you
    use for cdburning too. Just do "cdrecord dev=/dev/hdc" and that's it. No
    made-up SCSI bus numbers, no need to try to figure out what the right
    thing is, no crap.

    In fact, I hope that in linux-2.7.x the SCSI layer itself will start using
    the same interface, so that we can drop scsi-generic some day completely.
    The interface is totally generic, and doesn't have anything to do with IDE
    per se - ide-cd.c just needed to be cleaned up enough to be able to use
    it. The interface really just says "hey, you can push SCSI commands down
    the request queue" (and ide-cd.c will take the SCSI command and convert it
    into an ATAPI packet command - which is a pretty trivial transform).

    So right now, you can do "cdrecord dev=/dev/hdc ..", but because I didn't
    bother to try to figure out what the SCSI layer wants to do you can _not_
    do the simple "cdrecord dev=/dev/scd0 .." if you have a SCSI disk. That's
    nothing fundamental, I just don't think SCSI CD-RW's are very interesting
    any more, since they are overpriced and hard to find. I hope some SCSI
    fanatic will do the (probably trivial) addition to sr.c to accept the SCSI
    ioctl interface.

    (Hint for such SCSI users: you should just do:

    - call "scsi_cmd_ioctl()" in your ioctl routine, and if it returns
    ENOTTY that means that it wasn't one of the SCSI generic commands.

    - make the request queue handler understand that requests with the
    REQ_BLOCK_PC flag set are SCSI packet commands, and "req->cmd" contains
    the command, while "req->data" and "req->data_len" are the data for the
    command)

    - make sure that an open() with the O_NONBLOCK flag set will succeed even
    if the medium is not accessible (and will succeed even if it's a
    writable open).

    and that should be pretty much it).

    Linus

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