root mount error

[Kevin Oberman]

> Date: Tue, 28 Dec 2010 22:09:15 +0100
> From: Greg Byshenk <freebsd at byshenk.net>
> Sender: owner-freebsd-stable at freebsd.org
> 
> On Tue, Dec 28, 2010 at 11:08:44PM +0300, Michael BlackHeart wrote:
> > I'm no looking for help neither instructions how to build kernel. I'm
> > just installing 8.1 RELEASE and svn it up to last week 8-stable. And
> > going step-by-step of handbook installing kernel I'm having a trouble
> > - it seems than new kenel doesn't recognize my HDD. I'm not doing
> > something special, in that case I'm for shure mentioned it. I'm just
> > building GENERIC kernel without any configuration of system after
> > installation, to tweaks, no tunes, nothing. It's a new GENERIC kernel
> > and it can't find my HDD but 8.1 i386/amd64 releases works well and as
> > I remember something about month ago stable too.
> > >Now, a likely cause of your problem is the installation of a custom
> > >kernel with removed support for whatever your hard disk drive or raid
> > >controller is recognized as.
> > When it works it's just and ad0 hdd, no raid or special driver
> > I'm jsut trying to say than recent changes in kernel or kernel-modules
> > broke up my HDD support and I'd like to notice developres to check
> > where the problem is.
> > And of couse I've tried to switch SATA native mode and it doesn't
> > change anything.
> > Loader on it's own stage easily detects HDD and root partition so I
> > can just select old kernel and boot up, but I'm not shure how he gain
> > access to HDD to mfke any conclusion, probably through BIOS interrupts
> > but it's out of piont.
> > And for my pity I don't know how to dump demsg without having any
> > serial connection or usable disk drive, maybe to flash drive, but I
> > don't know how. And anyway there's no real kernel painc, it just asks
> > for root mountpoint.
> > 
> > And for shure I've got an 2.5" Hitachi HTS542516K9A300 160Gb SATA HDD
> > 
> > If you need any aditional info I'll give it all, just ask.
> 
> If you change to SATA native mode, then your HD may show up at a 
> different device (mine moved to ad8). If you go to native mode and
> issue a '?' when it fails to find the kernel, does it show any HD
> devices?

I would strongly urge that you start using labels instead of device
names for your disks. Labels don't change unless you explicitly change
them while drive names do.

Labels may be used in the fstab. E.G.:
# Device		Mountpoint	FStype	Options		Dump	Pass#
/dev/ufs/root		/		ufs	rw		1	1
/dev/ufs/tmp		/tmp		ufs	rw		2	2
/dev/ufs/var		/usr		ufs	rw		2	2
/dev/ufs/var		/var		ufs	rw		2	2

See 19.6 "Labeling Disk Devices" in the handbook for more information.
-- 
R. Kevin Oberman, Network Engineer
Energy Sciences Network (ESnet)
Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab)
E-mail: oberman at es.net			Phone: +1 510 486-8634
Key fingerprint:059B 2DDF 031C 9BA3 14A4  EADA 927D EBB3 987B 3751