Messages in this thread | | | Date | Sun, 28 Nov 2004 17:52:58 +0100 | From | Jens Axboe <> | Subject | Re: Is controlling DVD speeds via SET_STREAMING supported? |
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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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