kern/158569: ROOT MOUNT ERROR (caused by AHCI module)

Derek Schaeffer terrawattshock at
Fri Jul 1 16:10:01 UTC 2011

>Number:         158569
>Category:       kern
>Synopsis:       ROOT MOUNT ERROR (caused by AHCI module)
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Fri Jul 01 16:10:00 UTC 2011
>Originator:     Derek Schaeffer
>Release:        8.2-RC1
University of Louisville
[X at pcbsd-8686 /usr/home/X]$ uname -a
FreeBSD pcbsd-8686 8.2-RC1 FreeBSD 8.2-RC1 #4: Mon Dec 27 12:25:57 PST 2010 root at amd64
FreeBSD gives "ROOT MOUNT ERROR" when the kernel is loading modules at startup. This is regardless if the installation has been dual-booted or not. The problem appears to be the AHCI module.

Intel i7 980x processor
MSI Big Bang-XPower motherboard
XFX HD-485X-ZNFC Radeon HD 4850 video card
DDR3 2000 ram (16GB)
FreeBSD does not have AHCI enabled by default, however, PCBSD does.

In the loader.conf file,
will cause the problem to occur.
In the loader.conf file,
allows normal startup.

This problem was addressed in the (long) thread:

And in the PC-BSD forum:


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