Opened 11 years ago
Last modified 11 years ago
#11509 new enhancement
Host CD passthrough not consistant
| Reported by: | Perry G | Owned by: | |
|---|---|---|---|
| Component: | other | Version: | VirtualBox 4.2.6 |
| Keywords: | CD passthrough | Cc: | |
| Guest type: | all | Host type: | all |
Description
When choosing the host CD as the attached media device to be able to view video or use as a writeable CD/DVD, I need to set this with the guest stopped. After you change from the Host CD to an ISO, like the guest additions and then go back to the Host CD the passthrough is no longer enabled, requiring a complete shut-down of the guest to select and enable passthrough again.
I wonder if there is a way to make this default or at least add the CD/DVD passthrough as a VBoxManage controlvm function?
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Taking a deep breath... this is far more complicated than it seems at first glance.
The drive implementation behind "virtual CD" (whether it's from ISO or the host drive in non-passthrough mode) is totally different than when accessing the host drive in passthrough mode. In the former case it's fully virtualized (drive model info and capabilities are fully abstracted, only medium data is passed along), in the latter case the commands are only sanitized (preventing unsafe operations), but sent directly to the drive, and the I/O is passed back and forth as needed.
So it's technically impossible to switch between the two implementations EXCEPT by using DVD drive hot unplug/plug (as perceived by the guest OS). This is impossible on the IDE controller, on SATA it'd be feasible (but I'm not sure if there's a way to trigger this today)...