When issuing the CDROMPAUSE or CDROMRESUME on the vhba virtual CD-ROM devices, the ioctl returns -EIO on Linux 3.7.10. (I have not tried with a real CD device yet.)
I think PAUSE/RESUME command is valid only if device is in playing or paused state.
From INF8090: "If an audio play operation cannot be resumed and the Resume bit is one, the command shall be terminated with CHECK CONDITION status, 5/2C/00 COMMAND SEQUENCE ERROR. If the Resume bit is zero and an audio play operation cannot be paused, (no audio play operation has been requested, or the requested audio play operation has been completed), the command is terminated with CHECK CONDITION status."
From figure 185 on page 755 in INF8090, it would seem that pausing or resuming from initialized state (which is equivalent to "stopped" in cdemu) should not be possible. Unfortunately, my real optical drive does not seem to support audio play at all, so I cannot verify this.
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I think PAUSE/RESUME command is valid only if device is in playing or paused state.
From INF8090: "If an audio play operation cannot be resumed and the Resume bit is one, the command shall be terminated with CHECK CONDITION status, 5/2C/00 COMMAND SEQUENCE ERROR. If the Resume bit is zero and an audio play operation cannot be paused, (no audio play operation has been requested, or the requested audio play operation has been completed), the command is terminated with CHECK CONDITION status."
From figure 185 on page 755 in INF8090, it would seem that pausing or resuming from initialized state (which is equivalent to "stopped" in cdemu) should not be possible. Unfortunately, my real optical drive does not seem to support audio play at all, so I cannot verify this.