"Please insert an Xbox disc..." is confusing

[JayFoxRox]

If the kernel doesn't identify a valid disc it will launch into the dashboard.

In that case, this code is printing a confusing message:

xqemu-hdd-image/xboxdash/main.c

Lines 16 to 18 in ad4e8c5

	pb_show_debug_screen();
	debugPrint("Please insert an Xbox disc...\n");
	while(1) XSleep(1000);

This message will be shown, regardless of the current system state. If the user supplies a valid Xbox image (redump ISO), the message will still be printed in XQEMU (because of missing drive emulation).

We should probably add some code to check if a disc was inserted, and report the most common issues and current system state (disc drive information + kernel information).

[JayFoxRox]

I looked for information on how to detect a CD / DVD type. It appears to be done in software, the SMC only tells you wether the disc tray is opened / closed:

• From XBMC: DetectDVDType.
• From XBMC: GetTrayState.
  • Missing emulation in XQEMU: SMC tray state.

So we can use code that's similar to that in this XQEMU-Manager PR.

Additionally, we can query the DVD-X2 state from the drive, which is mode sense page 0x3E, to detect the broken XQEMU drive / authentication.