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Should both my IDE CD drives use ide-scsi?


I have two IDE CD drives, /dev/hdc is DVD player, and /dev/hdd is CD-RW. Through the magic of HOWTOs I have managed now to play audio CDs, play DVDs, and record audio CDs.  How it all works is still mostly a mystery.

The short question here is, should I uses scsi emulation for both drives, all the time?  Currently, I only use emulation on the CD-RW drive.

The long question is: my goal is not to just get this stuff working, but rather understand as much as possible about how the parts fit together to make a working system.  I've read a bunch of docs, but sometimes I'm not clear if they still apply, and if there's a debian way to do things.

So, I'd like help in filling in the blanks, if someone has time to go through this:

This is all on 2.4.17

To start with, here's my loaded modules at boot.

bumby:~# lsmod
Module                  Size  Used by    Tainted: P
NVdriver              818912  14  (autoclean)
loop                    8400   0  (unused)
emu10k1                51008   2
ac97_codec              9696   0  [emu10k1]
8139too                13152   1

After running "cdrecord -scanbus" I end up like this:

bumby:~# lsmod
Module                  Size  Used by    Tainted: P
NVdriver              818912  14  (autoclean)
loop                    8400   0  (unused)
sr_mod                 13144   0  (unused)
ide-scsi                7680   0
scsi_mod               50396   2  [sr_mod ide-scsi]
emu10k1                51008   2
ac97_codec              9696   0  [emu10k1]
8139too                13152   1

I assume this magic happens because of what I added to /etc/modutils/aliases (and thus to modules.conf after running update-modules):

options ide-cd ignore=hdd  # tell the ide-cd module to ignore hdd
alias scd0 sr_mod          # load sr_mod upon access of scd0 only
pre-install sg  modprobe ide-scsi # load ide-scsi before sg
pre-install sr_mod modprobe ide-scsi # load ide-scsi before sr_mod
# I've got ide-cd compiled in now
#pre-install ide-scsi modprobe ide-cd # load ide-cd   before ide-scsi

I don't really see from man modules.conf why "alias scd0 sr_mod" makes that happen on demand. It makes sense that a device request to /dev/scd0 might trigger a kmod request.  I guess I'm just missing something the modules.conf man page.

My ide-cd is compiled in

bumby:~# fgrep IDECD /boot/config-2.4.17-k7t266

So I'm disabling ide for /dev/hdd in lilo.conf

bumby:~# fgrep hdd /etc/lilo.conf
        append="apm=on apm=power-off hdd=ide-scsi"

So the "options" line above doesn't seen necessary (as the pre-install I've commented out).

That's the setup.

So I wonder:

1) cdrecord -scanbus only shows one ide-scsi drive (/dev/hdd -- my CD-R).  And also xcdroast only lists that one drive.  Should I add hdc=ide-scsi to lilo.conf and run both my CD/DVD (/dev/hdc) and my CD-R as ide-scsi?

2) if I did run both as ide-scsi, would that change the way I need to access my CD/DVD drive?  Currently I've got /dev/cdrom symlinked to /dev/hdc.  Would I then need to link it to /dev/scd0 so things like xmms still work?

Currently, in xmms in input plugin CD Audio Player's setup shows:

      Device: /dev/cdrom
   Directory: /cdrom

If both /dev/hdc and /dev/hdd were ide-scsi would/could I say Device: /dev/hdc instead?  Or would /dev/hdc no longer work if it was ide-scsi?

3) If I setup both CD drives as ide-scsi, then I suppose I need another "alias scd1 sr_mod" to auto-load modules on requests to that device, too.  True?

4) the modules setup still confuses me.  I don't really understand the reason for loading the modules on-demand instead of just loading them on boot or compiled in.  If I had ide-cd as a module, could I unload ide-scsi and end up with just IDE CD drives again?  And if so, what would be the reason for doing so?  With 1/2G RAM I'm not really worried about a few 100K of memory the modules take up.

5) I suppose I need to set those on-demand modules as "autoclean" so they will unload?

6) Back to question 4, I wonder if there's even reason to bother with this on-demand loading and the settings in modules.conf these days (with so much RAM).  Should I just load the ide-scsi support in an init.d script?

7) Finally, where does modconf fit in with all this?  Is it part of the modules.conf setup, or just a front-end for selecting and loading modules.  Where does it store what is loaded?

Thanks very much -- especially if you made it this far!

Bill Moseley

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