Re: cdrecord dev=ATA cannont scanbus as non-root

[J.A. Magallon]

On 2004.12.02, Jens Axboe wrote:
> On Wed, Dec 01 2004, Markus Plail wrote:
> > Jens Axboe <axboe@xxxxxxx> writes:
> > 
> > > On Mon, Nov 29 2004, J.A. Magallon wrote:
> > >> dev=ATAPI uses ide-scsi interface, through /dev/sgX. And:
> > >> 
> > >> > scsibus: -1 target: -1 lun: -1
> > >> > Warning: Using ATA Packet interface.
> > >> > Warning: The related Linux kernel interface code seems to be unmaintained.
> > >> > Warning: There is absolutely NO DMA, operations thus are slow.
> > >> 
> > >> dev=ATA uses direct IDE burning. Try that as root. In my box, as root:
> > >
> > > Oh no, not this again... Please check the facts: the ATAPI method uses
> > > the SG_IO ioctl, which is direct-to-device. It does _not_ go through
> > > /dev/sgX, unless you actually give /dev/sgX as the device name. It has
> > > nothing to do with ide-scsi. Period.
> > >
> > > ATA uses CDROM_SEND_PACKET. This has nothing to do with direct IDE
> > > burning, it's a crippled interface from the CDROM layer that should not
> > > be used for anything.  scsi-linux-ata.c should be ripped from the
> > > cdrecord sources, or at least cdrecord should _never_ select that
> > > transport for 2.6 kernels. For 2.4 you are far better off using
> > > ide-scsi.
> > 
> > Are you sure you don't mix ATA with ATAPI? I think ATA is equivalent to
> > dev=/dev/hdX. 
> 
> I did mix them up, my apologies til Magallon. As always you should just
> use -dev=/dev/hdX and it will work the best, there's no need to give ATA
> or ATAPI. They are too easy to mix up as the names don't really give you
> any hints on what access method they will utilize. Using -dev also means
> there's no reason to run -scanbus at all, since you know where the
> device is. If you don't, then you probably should be using k3b or some
> other helper to work out things for you.
> 

Ahh, I'm going to kick my head on the table...
Well, lets begin again. So:
- for 2.4, use ide-scsi
- for 2.6, use ATA
So cdrecord should stop to scan the ATAPI pseudo bus.

My problem is just that I want to set an easy way to burn for users.
In other systems you just hav an app onto you throw your mp3 and get 
an audio disc, or d'n'd your files and get a cd.
And I don want to tell people to rune mkisofs with a ton of options
(jolliet, rr, long names, etc...). So they must use a GUI tool.
The best I like nowadays is gnomebaker.

The thing is that all frontends use cdrecord. In many you can't specify
the device by hand, they just give you a menu based on cdrecord -scan
output. They should tell cdrecord to scan SCSI and ATA buses, but not ATAPI.

And now, as root:

werewolf:~# cdrecord dev=ATA -scanbus
...
scsibus1:
        1,0,0   100) 'HL-DT-ST' 'DVDRAM GSA-4120B' 'A102' Removable CD-ROM

werewolf:/store/tmp# cdrecord -dev=ATA:1,0,0 -dao -dummy *.iso
Driver flags   : MMC-3 SWABAUDIO BURNFREE 
Supported modes: TAO PACKET SAO SAO/R96P SAO/R96R RAW/R16 RAW/R96P RAW/R96R
Speed set to 7056 KB/s
Starting to write CD/DVD at speed  40.0 in dummy SAO mode for single session.
...

And as user:

werewolf:~> cdrecord dev=ATA -scanbus
...
cdrecord: Permission denied. Cannot open '/dev/hda'. Cannot open SCSI driver.
cdrecord: For possible targets try 'cdrecord -scanbus'. Make sure you are root.
cdrecord: For possible transport specifiers try 'cdrecord dev=help'.

werewolf:/store/tmp> cdrecord -dev=ATA:1,0,0 -dummy -dao *.iso
...
cdrecord: Permission denied. Cannot open '/dev/hda'. Cannot open SCSI driver.
cdrecord: For possible targets try 'cdrecord -scanbus'. Make sure you are root.
cdrecord: For possible transport specifiers try 'cdrecord dev=help'.

But:

werewolf:/store/tmp> cdrecord -dev=/dev/hdc -dummy -dao *.iso
...
cdrecord: Cannot allocate memory. WARNING: Cannot do mlockall(2).
cdrecord: WARNING: This causes a high risk for buffer underruns.
cdrecord: Operation not permitted. WARNING: Cannot set RR-scheduler
cdrecord: Permission denied. WARNING: Cannot set priority using setpriority().
cdrecord: WARNING: This causes a high risk for buffer underruns.
scsidev: '/dev/hdc'
devname: '/dev/hdc'
scsibus: -2 target: -2 lun: -2
Warning: Open by 'devname' is unintentional and not supported.
Linux sg driver version: 3.5.27
WARNING ! Cannot gain SYS_RAWIO capability ! 
: Operation not permitted
...
Driver flags   : MMC-3 SWABAUDIO BURNFREE 
Supported modes:                                  < EMPTY AGAIN !!!!!
cdrecord: Drive does not support SAO recording.
cdrecord: Illegal write mode for this drive.

werewolf:/store/tmp> ll /dev/hdc
brw-rw-rw-  1 magallon cdwriter 22, 0 2004.12.01 23:27 /dev/hdc

(pam did it for the console ;))

There are some bugs here:
- One in cdrecord, that exits as soon as it can't open a device, instead
  of trying till it gets the cdwriter.
- Other in cdrecord, the system does not behave the same way if I
  give /dev/hdc or ATA:1,0,0.
- Other in the kernel, that does not allow to query capabilities of the
  drive to a normal user.

I can hackpatch cdrecord, but have no idea of what to do with the kernel.
I remember there were some mails time ago about adding allowed commands to
cdrom/cdwiters, but can't find them.

Perhaps, someday, somwhere, I could burn a disc in Linux as plain user.

Thanks for bearing me...

--
J.A. Magallon <jamagallon()able!es>     \               Software is like sex:
werewolf!able!es                         \         It's better when it's free
Mandrakelinux release 10.2 (Cooker) for i586
Linux 2.6.10-rc2-jam4 (gcc 3.4.1 (Mandrakelinux 10.1 3.4.1-4mdk)) #2

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