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Re: Virtual Device



Am 18.10.2006 um 19:30Uhr schrieb Kevin Elliott:

The reason why your DiskImage idea won't work is that CD's are accessed differently than standard block media (the reasons are complicated and messy, mostly having to do with the fact that the CD standard is relatively old and wasn't originally designed as a data storage medium). If you manage to make and existing image look like a CD in IOKit, IOKit does exactly what you want and starts treating that image as a CD. Which promptly breaks because it's NOT a CD and isn't expecting to be treated like one. I doubt your getting that far- it would be pretty tricky to get to that point and is a lot more involved than tweaking registry keys. It's more likely that you've corrupted the image in some way and the DiskImage kext is choking.

True, all tries to modify the disk-image entries in the IOReg to make it look like a CD drive - failed...

I've started to write the virtual driver (based on Hello I/O Kit example). Arvind has sent me a link to an interesting thread: 'Faking an IOKit Device' http://lists.apple.com/archives/darwin-drivers/2005/ Aug/msg00104.html

I'm not at the point to handle the IO process, yet. My idea is to redirect the IO to a disk-image, that way I don't have to take care about the different formats. Simplified: IO-Request -> VirtualDevice - > Custom Redirect IO-Routine -> disk image. The user will end up with a normal disk-image. On the other hand, it may be more compatible to create custom images with a 1:1 track/sector structure.

For the drive identification I thought the best way would be to let the user select a device from the DiscRecordingEngine's DeviceSupport.drprofile/VendorSupport.drprofile list.


...I'd suggest you take a closer look at the CD/DVD burning specifications and tackle it from that direction, rather than trying to jury rig something with the existing DiskImage architecture.
Best of luck! If nothing else it sounds like a really interesting challenge!

Thanks Kevin. Sure, I'll need to figure out the specs in detail. _______________________________________________
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References: 
 >Virtual Device (From: Rene Trost <email@hidden>)
 >Re: Virtual Device (From: Michael Smith <email@hidden>)
 >Re: Virtual Device (From: Rene Trost <email@hidden>)
 >Re: Virtual Device (From: Kevin Elliott <email@hidden>)



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