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    SubjectRe: Is controlling DVD speeds via SET_STREAMING supported?
    On Sun, Nov 28 2004, Thomas Fritzsche wrote:
    > Hi,
    >
    > (please CC me because I'm not subscribed to the list)
    >
    > >> What Kernel do you use?
    > >
    > > Linux tienel 2.6.10-rc2-mm1 #1 SMP Wed Nov 17 01:19:53 EET 2004 i686
    > > GNU/Linux
    >
    > Maybe you can give a 2.4.27'er kernel a try.
    >
    > >
    > > Actually now that I rebooted (for DVD flashing) and started back into
    > > linux, after running dvdspeed it also says:
    > > "scsi: unknown opcode 0xb6" (which is SET_STREAMING). Code for this is
    > > in drivers/block/scsi_ioctl.c, and if I read it right, it can't prevent
    > > root from executing that command.
    >
    > I have the same impression after reading drivers/block/scsi_ioctl.c . I
    > think you will need root permission to send this command, RW-Permission
    > for the device file is not enough! Did you try this as root?

    You just need to add SET_STREAMINIG as a write-safe command, then it
    will work as a regular user. Hmm, it is already added as write safe. You
    don't have write permission on the device, then.

    > But I'm wondering that scsi_ioctl.c comes into play, because It's a
    > ATAPI-Device. Isn't it? Do you use the scsi emulation? If so please try
    > without.

    The 'scsi' in the name doesn't refer to the transport used, but the
    command set being scsi-like. ide-scsi emulation has nothing to do with
    it.

    > > I modified your speed-1.0 to open device O_RDWR, didn't help.
    > > I modified it to also dump_sense after CMD_SEND_PACKET, it's just
    > > duplicate packet.
    >
    > No this will definitively not solve this issue. I will try to check this
    > in the kernel, but because I'm not a kernel developer I will CC Jens
    > Axboe. Maybe he can help?

    Just fix the permission on the special file. Additionally, the program
    must open the device O_RDWR.

    --
    Jens Axboe

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