Problem booting 5.4

Doug White dwhite at
Fri May 13 15:26:56 PDT 2005

On Thu, 12 May 2005, Rainer Duffner wrote:

> Hi,
> I installed FreeBSD5.4 on a server with a 3ware 7006-2 controller and
> two 120GB disks as RAID1
> I cannot boot this install. (I get some kind of panic or endless loop,
> but the display is re-painted so fast I cannot read it).
> What I *can* do is insert my SuSE9.2-pro cd1, boot from that and at the
> grub-menu say "boot from harddisk".
> That boots FreeBSD.
> On advice from IRC, I tried:
> # boot0cfg -B twed0
> -which leads to this output
> boot0cfg: write_mbr: /dev/twed0: No such file or directory

This is a erroneous message. The actual problem is:

   484 boot0cfg NAMI  "/dev/twed0"
   484 boot0cfg RET   open -1 errno 1 Operation not permitted

This is a known problem with certain MBR layouts. To work around this
problem, set:

sysctl kern.geom.debugflags=16

then try your boot0cfg. There's a protection mechanism that sometimes gets
confused by certain partition table layouts. Flag 16 disables that
protection.  I don't recommend running this unless you are explicitly
trying to updating something in a partition table-like area; its very easy
to destroy your system with the flag set!

Doug White                    |  FreeBSD: The Power to Serve
dwhite at          |

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