gpart and mbr give "no operating system" message at boot.

Polytropon freebsd at
Fri Sep 7 23:16:07 UTC 2012

On Fri, 07 Sep 2012 17:00:24 -0600, markham breitbach wrote:
> I was always under the impression that partition 3 was not to be touched as the "raw"
> partition, so figured it was best left alone.

No, that is regarding traditional partitioning. But it's
not the 3rd partition, it's the 'c' partition, which means
nothing more or less than "the whole device" or "the whole
slice". In today's FreeBSD /dev representation, the 'c' is
left out, e. g. /dev/ad0c = /dev/ad0, and /dev/da3s2c = /dev/da3s2.
For GPT partitions, that doesn't matter. It's only relevant
for the kind of partitions disklabel (bsdlabel) creates
inside a slice or directly on the device.

Reserved names (or those with special purpose) are 'a'
for a bootable partition, 'b' for a swap partition and
'c' for "the whole slice or disk". I think even 'd' has
had a special meaning, but I didn't encounter it yet,
even though I'm using FreeBSD since 4.0. :-)

Partitions created with the gpart / gpt tools usually use
e. g. /dev/ad0p1 and so on for partitioning, if I remember
correctly. Additionally, I typically point to

to encourage the use of labels, because that lets you leave
devices names alone.

More information can be found here:

And also

regarding labels (GEOM labels, UFS labels, UFSIDs).

> I was mostly concerned with installing MBR so it would still be compatible with
> sysinstall, although I can't really think of a terribly good reason not to go GPT.

Maybe that is significant only on older hardware where you
intendedly want to preserve the "traditional" approach of
MBR partitioning, maybe to keep compatibility with other
systems that have trouble with GPT layouts.

> Installing the bootcode gets me a step closer, but is now puking at the loader. I'm not
> sure if this is because the bootcode is coming from and 8.1 install, but at this point I'm
> pretty much out of time and out of patience for this, since it is something of a bandaid
> situation anyway.

The version number should not be the problem. It's only important
that the boot elements installed refer to the layout that is
present on disk correctly.

Magdeburg, Germany
Happy FreeBSD user since 4.0
Andra moi ennepe, Mousa, ...

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