Re: Loader, MBR and the boot process

[Matthew Seaman]

Andriy Gapon wrote:

on 25/01/2010 04:41 Robert Noland said the following:

On Mon, 2010-01-25 at 07:57 +1100, Mark Andrews wrote:

     offset  The offset of the start of the partition from the beginning of
             the drive in sectors, or * to have bsdlabel calculate the correct
             offset to use (the end of the previous partition plus one, ignor-
             ing partition `c'.  For partition `c', * will be interpreted as
             an offset of 0.  The first partition should start at offset 16,
             because the first 16 sectors are reserved for metadata.

Ok, now this has my attention... My gut feeling right now is that this
is a bug in geom_part_bsd.  I don't understand why the label isn't
protected.  (Adding -b 16 when adding the swap partition fixes this)
Another project to goes on my list...

If anyone knows why this is done like this... please share.

I presume that this is for purely historic reasons.

I believe this has been known about since 5.x days:

  http://www.freebsd.org/cgi/query-pr.cgi?pr=72812

As far as I recall, sometime around 6.1-RELEASE this should have been

swap or putting a filesystem there needs the 16 sector offset.

        Cheers,

        Matthew

--
Dr Matthew J Seaman MA, D.Phil.                   7 Priory Courtyard
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fixed. It certainly seems to be the case that it is harmless to have a plain swap partition start at offset 0, but anything else, like encrypted

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