random problem with 8.3 from yesterday

Erich Dollansky erichfreebsdlist at ovitrap.com
Sun Feb 26 04:04:33 UTC 2012


On Sunday 26 February 2012 00:17:40 Scott Bennett wrote:
>      On Sat, 25 Feb 2012 08:56:24 -0800 Kevin Oberman <kob6558 at gmail.com>
> wrote:
> >On Sat, Feb 25, 2012 at 2:27 AM, Scott Bennett <bennett at cs.niu.edu> wrote:
> >> =A0 =A0 On Wed, 22 Feb 2012 13:34:36 +0700 Erich Dollansky
> >> <erich at alogreentechnologies.com> wrote:
> >>
> >>>I got a new thumb drive which was FAT formatted. I use this script to cha=
> >nge this:
> >>>
> >>>!/bin/tcsh
> >>>#
> >>># This script format a thumb drive connected to USB as da0.
> >>>#
> >>>printf "You have to run this script as 'root' to succeed.\n"
> >>>printf "Warning this script will delete all your data from /dev/da0. Cont=
> >inue? > "
> >>>set Eingabe =3D $<
> >>>if ("$Eingabe" =3D=3D "y") then
> >>> =A0 printf "\nDeleting the device "
> >>> =A0 dd if=3D/dev/zero of=3D/dev/da0 bs=3D1k count=3D1
> >>> =A0 printf "\nWriting the BSD label "
> >>> =A0 bsdlabel -Bw da0 auto
> >>
> >> =A0 =A0 Hmmm...so no MBR and no GPT either? =A0Just the bare device? =A0I=
> > guess
> >> I haven't tried that, so I don't know what that would do.
> >
> >Call me a bit confused, but I thought -B did write an MBR. It always
> >has seemed to do so for me, at any rate. From man bsdlabel:
> >"Installing Bootstraps
> >     If the -B option is specified, bootstrap code will be read from the fi=
> >le
> >     /boot/boot and written to the disk."
> >Or am I not understanding something?
it looks like that I have left the -B option by mistake for many years in there.

>      I guess I understand the part that you quoted above as meaning that
> the bootstrap code would be copied to the bootstrap sectors.  However, as
> I interpret it, the bsdlabel command does not write a MBR, which would
> include the slice map for the device.  Further, Erich's later commands did
> not specify a slice number.  In short, it looks to me as though he may have
> ended up with the initial boot code where it belonged at the start of the
> device, but the boot code looks for the slice map, which isn't there, so
> it should not be possible to boot a kernel because the bootstrap code

There is also no kernel, no binary, nothing what could be started on the device.

> would not be able to find it.  But as far as simply mounting a file system,
> I really don't know whether it should work to have a BSD label written to
> a bare device with neither a MBR nor a GPT to find that label.  IOW, would
> the device node to be used in the mount operation have been created?
>      Note to Erich:  did you look in /dev and /dev/ufs to see whether all
> of the device files that you expected to be there were, in fact, present
> before you attempted the mount?

It was there. I extra checked.

As I said before, since I got the file system onto the device, the device can be used as expected.


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