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    SubjectRe: CD writing in future Linux (stirring up a hornets' nest)
    On 2/10/06, Joerg Schilling <> wrote:
    > "D. Hazelton" <> wrote:
    > > And does cdrecord even need libscg anymore? From having actually gone through
    > > your code, Joerg, I can tell you that it does serve a larger purpose. But at
    > > this point I have to ask - besides cdrecord and a few other _COMPACT_ _DISC_
    > > writing programs, does _ANYONE_ use libscg? Is it ever used to access any
    > > other devices that are either SCSI or use a SCSI command protocol (like
    > > ATAPI)? My point there is that you have a wonderful library, but despite
    > > your wishes, there is no proof that it is ever used for anything except
    > > writing/ripping CD's.
    > Name a single program (not using libscg) that implements user space SCSI and runs
    > on as many platforms as cdrecord/libscg does.

    I have 2 technical questions, and I hope that you will take the time
    to answer them.

    1) extract from the README of the latest stable cdrtools package:

    Linux driver design oddities ******************************************
    Although cdrecord supports to use dev=/dev/sgc, it is not recommended
    and it is unsupported.

    The /dev/sg* device mapping in Linux is not stable! Using dev=/dev/sgc
    in a shell script may fail after a reboot because the device you want
    to talk to has moved to /dev/sgd. For the proper and OS independent
    dev=<bus>,<tgt>,<lun> syntax read the man page of cdrecord.

    My understanding of that is you say to not use dev=/dev/sgc because it
    isn't stable. Now that you've said that bus,tgt,lun is not stable on
    Linux (because of a "Linux bug") why is the b,t,l scheme preferred
    over the /dev/sg* one ?

    2) design question:

    - cdrecord scans then maps the device to the b,t,l scheme.
    - the libsg uses the b,t,l ids in its interface to perform the operations

    So now, if cdrecord could have a new option called -scanbusmap that
    displays the mapping it performs in a way that people can parse the
    output, I think that will solve most issues.

    cdrecord already has this information available, it just doesn't display it:

    $ cdrecord debug=2 dev=ATAPI -scanbus 2>&1 | grep INFO
    INFO: /dev/hdc, (host0/bus1/target0/lun0) will be mapped on the
    schilly bus No 0 (0,0,0)
    INFO: /dev/hdd, (host0/bus1/target1/lun0) will be mapped on the
    schilly bus No 0 (0,1,0)

    It could perform in the following way:

    $ cdrecord dev=ATAPI -scanbusmap

    0,0,0 <= /dev/hdc
    0,1,0 <= /dev/hdd

    Are you accepting such a patch?

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      Last update: 2006-02-10 16:41    [W:0.022 / U:63.904 seconds]
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