[issue1127] cdrom drive not detected

[Ed Berger]

I have a similar error on my home "debranded HP media PC" which is a 
Core2Duo intel chipset based motherboard, SATA hard disk and DVDRW, with 
bios option set to AHCI mode instead of IDE mode.  With default boot 
options (no keyboard input) the CD fails to boot with same rootvp can't 
be found, apparently trying acd0, which doesn't exist under AHCI, and 
ends debugger prompt.  If I watch the boot process and choose the "no 
AHCI" boot option, It finds the DVD rom and works fine, presumably 
because acd0 exists under nata.  On a slightly older version, It would 
fail to the mountroot prompt and typing in cd9660:cd0 works sometimes or 
not with an "Device is in process of getting ready" type of message, 
showing up...

tpreitzel <tpreitzel at hotmail.com> added the comment:

I receive the following error when attempting to boot the CDROM iso:

iso_mountroot: can't find rootvp

This error sends the boot process into the debugger. Actually, I've had this
problem with the last several versions of DragonFly BSD. Apparently, this
problem is significant as others have experienced it also.