CDROM Boot Hangs But Only Under 6.x

Ted Mittelstaedt tedm at
Fri Dec 28 01:17:09 PST 2007

> -----Original Message-----
> From: owner-freebsd-questions at
> [mailto:owner-freebsd-questions at]On Behalf Of Tim Daneliuk
> Sent: Tuesday, December 25, 2007 11:15 PM
> To: FreeBSD Mailing List
> Subject: Re: CDROM Boot Hangs But Only Under 6.x
> Ted Mittelstaedt wrote:
> <SNIP>
> >
> > If your MB is new it should work.  Older MB's have problems with
> > the "new way" to boot off an optical cd.  You can try BIOS/CMOS
> > updates from the motherbard mfg if they are available.  Sometimes
> > even back-flashing to older BIOS fixes it.
> This is a brand new ABIT mobo w/latest bios on board.
> >
> >> 3) Reordering/removing memory sticks made no difference.  I am running
> >>     a memory test ATM just to be sure, but so far, the memory
> seems fine.
> >>
> >> 4) No amount of poking around in the BIOS settings seems to
> help either.
> >>
> >> I am starting to suspect the MOBO.  If I stick a couple of cards in the
> >> two available PCI slots, the system has trouble taking me into the BIOS
> >> screen.  I have to remove the cards to reliably get into the BIOS
> >> settings menu.  I wonder if this is one of those situations where there
> >> are not enough IRQs to go around.
> >>
> >
> > If it's a new MB the PCI cards are probably too old/slow to work right.
> I thought that even modern PCI busses would fall back to the old
> speeds.  I've had not trouble with any of my other rather new
> mobos, running, say, old Adaptec controllers.
> >
> > Another thing to check is if the MB has any overclock settings turned
> > on, these will screw up booting, going into BIOS, and some PCI cards.
> > Go to BIOS and select "reset to factory settings" which turns off all
> > the go-fast stuff.  And make sure you confirm the CPU speed in BIOS
> > with the actual speed stamped on the CPU.
> I've reset the BIOS to the most conservative mode, no overclocking, etc.
> >
> > Sometimes you just got to stick a floppy disk drive on the thing and
> > boot from the 4 boot floppies then do an FTP install.  I have about
> > a dozen servers among the collection I manage that are like this -
> > some are even newer ones.
> I would *love* to know just where boot is getting lost.  In the case
> of your servers, do you see the same symptoms I am seeing: The
> kernel loading progress prompt gets painted (most of the time,
> sometimes it does not even make it that far) and the booting
> seizes up?

No, they won't even load the boot loader.  The symptoms your describing
are classic for PIO/UDMA negotiation issues.  In other words, the
connection from the atapi controller to the optical drive is being
negotiated by BIOS as UDMA and negotiated by the FreeBSD boot kernel
as UDMA but a bug somewhere is causing the bus to corrupt data.  The
usual fix is to switch to PIO mode.  The only problem with this
is that you have already swapped optical drives, and I'd assume that
at least one of the swaps didn't support UDMA mode (thus forcing
PIO mode) you also said you already checked this, and even if it did
negotiate UDMA it would be UDMA33 not anything faster that would require
the special high speed IDE cables so we can probably rule out a
crap CDROM cable.  Lastly, the default on the ata driver is supposed
to be PIO mode anyway for optical drives.


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