Should both my IDE CD drives use ide-scsi?
Hello,
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
CONFIG_BLK_DEV_IDECD=y
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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