Booting FreeBSD 8.0-RC1 from usb stick

Gavin Atkinson gavin at
Tue Sep 29 17:10:22 UTC 2009

On Tue, 2009-09-29 at 16:51 +0200, Marius Nünnerich wrote:
> On Tue, Sep 29, 2009 at 16:03, Gavin Atkinson <gavin at> wrote:
> > On Tue, 2009-09-29 at 14:40 +0200, Marius Nünnerich wrote:
> >> 2009/9/29 Andrey V. Elsukov <bu7cher at>:
> >> > Marius Nu"nnerich wrote:
> >> >>
> >> >> Explicitly setting the root partition
> >> >> (vfs.root.mountfrom="ufs:/dev/da0s1a") in /boot/loader.conf does not
> >> >> help either: Again, the system knows which partition it should mount
> >> >> to "/", but it fails to do so. (vfs.root.mountfrom.options=rw was set
> >> >> too).
> >> >
> >> > It's known problem and we are waiting for fix. There is a race between
> >> > USB and CAM/SCSI subsystems.
> >>
> >> OK, thank you! Is there a PR open for this?
> >
> > I think your problem is probably usb/138798.
> Thanks! I hoped there would be some quick fix like putting some DELAY
> into CAM or usb to go ahead for now but it isn't. Anyone has an idea
> for where to put this or a patch to try? I suppose usb should finish
> before CAM comes along?

Hmm, that PR might not be your problem.  Do you see the USB stick probe
and appear after the kernel has tried to mount it, like in that PR, or
do you see the USB stick probe before mountroot is attempted, but it
still fails?

Either way, you could try the attached hack. Be aware that this really
is not the correct fix, but might at least be enough to get you going
until the correct fix is in place.

No guarantees, warranty etc.

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