CDemu - a virtual CD/DVD drive for Linux

Rok Mandeljc wrote:
> Hey everyone,
>
> as you've probably noticed, Chia-I Wu wrote an alternative to
> cdemu-module, the kernel module that userspace-cdemu uses. Instead of
> emulating CD-ROM device like cdemu-module does, it emulates SCSI host
> bus adapter, which simplifies the code and makes it most robust. And,
> more importantly, it works with HAL daemon out-of-box, which means you
> can get discs automatically mounted when they're inserted, just like
> with real devices. (consequently, it also means that cdemu devices now
> show up in Wine...)
>   
Hi
    How about build an iSCSI daemon instead of a kernel module ?
So it will be completely user-space, no kernel module needed.
It can be accessed by iSCSI initiator like open-iscsi,and even export
it thought internet.

> I've uploaded modified code along with vhba module to
> http://kabelkaos.net/cdemu/cdemu-vhba if you want to test it.
>
> Note that when you install daemon, you must to pass --sysconfdir=/etc to
> configure regarless of the prefix you use in order for config files to
> be installed in correct place. And, arguments to daemon have changed -
> if you run it manually, see 'cdemud --help' for details.
>
> Regards,
>     Rok
>
> -=-=-=-=-=-
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> and remove all doubt.
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Hi!

>     How about build an iSCSI daemon instead of a kernel module ?
> So it will be completely user-space, no kernel module needed.
> It can be accessed by iSCSI initiator like open-iscsi,and even export
> it thought internet.

As far as I can see, what changed is just the kernel-module (so you DO  
need a kernel module). The patch to the daemon is so that it cooperates  
better with the news scsi kernel-module and stuff needed for the "old"  
module has been removed. But that is just how I understood it.

Cheers
Matthias
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Hey Rok!

I downloaded and compiled the vhba-module and the modified cdemu-daemon  
 from http://www.kabelkaos.net/cdemu/cdemu-vhba/ and it compiled without  
any problems. The kernel-module loads without any problems, but the daemon  
won't start. Neither with the supplied init script (i'm on ubuntu) nor by  
invoking cdemud manually (it retutns 0).

Any ideas?

Regards
Matthias

There is a bug in init-script.

try modify /etc/init.d/cdemu-daemon
edit this line:
start-stop-daemon --start --quiet --exec "$DAEMON" -- "$DAEMON_ARGS"
>/dev/null 2>&1
to
start-stop-daemon --start --quiet --exec "$DAEMON" -- $DAEMON_ARGS
>/dev/null 2>&1

or start daemon manually by
# cdemud --num-devices=1 --ctl-device=/dev/vhba_ctl --audio=alsa
--audio-device=default

Matthias Niess wrote:
> Hey Rok!
>
> I downloaded and compiled the vhba-module and the modified cdemu-daemon  
>  from http://www.kabelkaos.net/cdemu/cdemu-vhba/ and it compiled without  
> any problems. The kernel-module loads without any problems, but the daemon  
> won't start. Neither with the supplied init script (i'm on ubuntu) nor by  
> invoking cdemud manually (it retutns 0).
>
> Any ideas?
>
> Regards
> Matthias
>
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> Download DB2 Express C - the FREE version of DB2 express and take
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>

Hey everyone,

Sorry for lack of response from me, but my email provider was having
technical difficulties this week, causing mail to be delivered late or
not at all...

Anyway, I've updated tarballs at http://kabelkaos.net/cdemu/cdemu-vhba;
most important changes (though nothing really big):
 - Chia-I Wu did some more work on module, making it more robust and
reliable
 - fixed initscripts
 - implemented MODE SENSE 6  command which seems to be used by SCSI
instead of MODE SENSE 10 by default; now device caps are properly
detected and listed by hal
 - some minor improvements in daemon's debug code

Building an iSCSI daemon seems an interesting idea and I'll look into it
(unless someone else does it) - my main concerns at this time are
whether cdemu could co-exist with real iSCSI daemon and whether it would
bring us any benefits over current method (aside from no kernel module).
Also, does iSCSI initiator set up host device in sysfs
(/sys/class/scsi_host/hostX)?

Regards,
    Rok

Index: vhba-module/Makefile
===================================================================
--- vhba-module.orig/Makefile
+++ vhba-module/Makefile
@@ -1,17 +1,18 @@
 obj-m += vhba.o
 
-MODULE	:= vhba
 KDIR	:= /lib/modules/`uname -r`/build
 KMAKE	:= $(MAKE) -C $(KDIR) M=$(PWD)
 
-all: $(MODULE).o
+all: modules
 
-$(MODULE).o: $(MODULE).c
+modules:
 	$(KMAKE) modules
 
-install:
+modules_install:
 	$(KMAKE) modules_install
 
+install: modules_install
+
 distdir:
 	cp vhba.c $(distdir)
 	cp Makefile $(distdir)
@@ -24,5 +25,5 @@ dist-gzip:
 	package=vhba-module; \
 	mkdir $$package; \
 	cp vhba.c Makefile $$package; \
-	tar zcf $$package.tar.gz $$package; \
+	tar -czf $$package.tar.gz $$package; \
 	rm -rf $$package

Index: vhba-module/vhba.c
===================================================================
--- vhba-module.orig/vhba.c
+++ vhba-module/vhba.c
@@ -113,15 +113,10 @@ static struct vhba_device *vhba_device_a
 	return vdev;
 }
 
-static struct vhba_device *vhba_device_put(struct vhba_device *vdev)
+static void vhba_device_put(struct vhba_device *vdev)
 {
 	if (atomic_dec_and_test(&vdev->refcnt))
-	{
 		kfree(vdev);
-		vdev = NULL;
-	}
-
-	return vdev;
 }
 
 static struct vhba_device *vhba_device_get(struct vhba_device *vdev)

On Jun 7 2007 23:11, Rok Mandeljc wrote:

>Anyway, I've updated tarballs at http://kabelkaos.net/cdemu/cdemu-vhba;

You might want to...

 - use kernel coding style (brace placement)

 - pr_debug() instead of hand-crafted DPRINTKs

 - turn DATA_TO_DEVICE and DATA_FROM_DEVICE into static inline functions



	Jan
--

On Wed, Jun 06, 2007 at 03:13:52AM +0800, Zealot wrote:
>     How about build an iSCSI daemon instead of a kernel module ?
> So it will be completely user-space, no kernel module needed.
> It can be accessed by iSCSI initiator like open-iscsi,and even export
> it thought internet.
I didn't know about iSCSI until now...

If implementing iSCSI protocol doesn't add too many complexities to
cdemud-daemon, it is definitly worth trying.

And I'll be working on vhba anyway.  Since it is an exercise I assigned
to myself while reading "Linux Device Drivers" :)

-- 
Regards,
olv