Fwd: Re: Fwd: [MPlayer-users] SCSI emulation

[H}kan Hjort]

Sun Jan 05 2003, Bob Lockie wrote:
> H}kan Hjort wrote:
> >Sat Jan 04 2003, Bob Lockie wrote:
> >>H}kan Hjort wrote:
> >>   
> >>
> >>>Could you try the following too?  This is a small utility that accesses 
> >>>and prints a bunch of info from the drive and disc in it.
> >>>
> >>>     
> >>>
> >>Of course it is flaky and seems to work today. :-(
> >>I ran the tests anyways, maybe the "invalid argument" errors should not 
> >>be there anyways.
> >>
> >Humm.. wierd.
> >
> >>>http://www.dtek.chalmers.se/~dvd/dist/dvd_test.tar.gz
> >>>
> >>>compile by running the 'build.sh' script and run with
> >>>'./dvd_test /dev/dvd >& dvd_test.logX'
> >>>this should print a bunch of stuff. Do this for the different 
> >>>configurations
> >>>dma on/off ide-scsi on/off and send the output to me.  
> >>>Does it make any difference depending on the DVD movie/disc used?
> >>>
> >>No, it failed on the 3 discs I tried.
> >>
> >>>Ejecting / intering the disc?  Having it mounted or not?  
> >>>I'll write a summary of anything intresting for the list.
> >>>
> >># hdparm -d /dev/sr1
> >>/dev/sr1 not supported by hdparm
> >>How do I enable DMA for an emulated IDE DVD drive?
> >>   
> >>
> >
> >Changing the DMA status is done by reprogramming the IDE chipset/bus,
> >so even when it's using ide-scsi emulation you need to use the underlying
> >ide node to change it.  So /dev/hdc for you, and then read/test on the
> >/dev/sr1 node.  Your sure sr1 is the DVD?
> >
> That was my guess but /dev/hdc disappears when I use SCSI emulation.
> # ll /dev/hdc
> ls: /dev/hdc: No such file or directory
> 
A side effect of using devfs perhaps?  There should be some trace of
the ide device still, should there not?  Or there will be a general
problem with things like DMA!

[snip] 
> Maybe I forgot to change the link for /dev to /dev/sr1.
> With SCSI emulation it appears that the /dev/dvd link cannot point to 
> /dev/cdrom (even if that points to the correct device).
> 
That's strange.

The only thing I see that migth mess things up here is that for CSS
authentication and key exchange one has do make a few ioctl calls, to
ba able to do that one needs to have both read & write permission.

For SCSI emulation you had
lr-xr-xr-x    1 root     root            8 Jan  4 07:00 /dev/dvd -> /dev/sr1
brw-rw----    1 root     cdrecording  11,   1 Dec 31  1969 /dev/dvd

and for normal IDE
lr-xr-xr-x    1 root     root           10 Jan  4 15:12 /dev/dvd -> /dev/cdrom
brw-rw-rw-    1 root     root      22,   0 Dec 31  1969 /dev/dvd

So unless you are a member of the cdrecording group you don't have 
'rw' permissions in the SCSI emulation case. 

Another thing is that for all the logs reading sector (lba) 512 and later
failed.

-- 
Håkan Hjort
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