Name: changer Version: 20000201 Kernelver: 2.x.x Status: 9 Author: Jeroen Massar Maintainer: Jeroen Massar Description: /dev/changer - Transparent IDE Cd Changer Device Date: 2001-07-14 Descfile-URL: http://unfix.org/projects/changer/changer.desc Download-URL: http://unfix.org/projects/changer Homepage-URL: http://unfix.org/projects/changer Manual-URL: http://unfix.org/projects/changer **** NOTICE **** I've kinda stopped patching this driver any further. First and biggest reason is simply because there are no intensions whatsoever from the main kernel maintainers to include this patch into the main tree, which currently would require me to create a patch for every single version of the kernel. And as I really don't have the time for it and got much better things to do I stop doing it... it's as simple as that. Would there be any intention whatsoever that they would decide it to become a part of the kernel I will do my best to get it in straight away though... but as you've prolly guessed that won't be for a long time... **** NOTICE **** Detailed Description of the patch Normally it isn't allowed to mount all the discs of a changer at once, that is because when you mount one slot you can't change to another anymore, because the cdrom gets locked. And of course you'll have to unmount it and then you'll have to change discs by hand. Ok you could do this with a script... but what if you want to share the drives with NFS or Samba and you don't want people to have to hassle with the scripts... let alone when multiple people try... This little wrapper solves this problem. When it is loaded by the kernel it seeks in the Unified CdRom driver list and checks for changers (capacity>1&changable). It adds these devices to an changer-internal list, opens them and adds them to the changer-devices minor list. The devices changer:minor can then be mounted like any other normal cdrom device, as it acts like a single cdrom device... The other minors can also be mounted at the same time as the changer-wrapper will change to the appropriate slot when it needs access to it. NOTE: This driver works with ANY cdrom driver, not only IDE but it should also work with scsi and other drivers supporting the Unified CdRom driver changing mechanism. The driver works for any kernel having the Uniform Cdrom Driver. This mainly includes the 2.2.x and 2.3.x series and also the later 2.1.x series. I am currently busy with the following items: * Trying to get this driver into the 2.2.x / 2.3.x kernel tree. * Trying to get an "official" device number instead of the 42 (example number). Which ain't bad and it does the work, 42 is the solution... * Command queing & reordering. * Device locking. Unfortunatly the first two things see to be very difficult to attain. So if you want /dev/changer into the kernel tree try starting a thread on a linux list or complain with the kernel folks. Cause even though Linux is the peoples OS, it sure is hard to get into the kernel tree which apparently is closed and only accessible for a few... The third item is thought out (see changer.c) it only has to get implemented. The last item (device locking) would require a huge rewrite of the Linux kernel concerning device handling and locking.