absolute vs. relative offsets in disklabel
John Baldwin
jhb at freebsd.org
Mon Aug 7 21:54:44 UTC 2006
On Monday 07 August 2006 17:05, Roman Kurakin wrote:
> John Baldwin:
>
> >On Sunday 06 August 2006 10:59, Dmitry Marakasov wrote:
> >
> >
> >>* Dag-Erling Sm?rgrav (des at des.no) wrote:
> >>
> >>
> >>>>Recent `disklabel differences FreeBSD, DragonFly' thread gave me a
> >>>>thought - why do we have absolute offsets in disklabel?
> >>>>
> >>>>
> >>>We don't, AFAIK. Since the transition to GEOM, the offsets are
> >>>relative to the start of the containing provider.
> >>>
> >>>
> >>It has nothing to do with GEOM, it's ondisk format of disklabel. I've
> >>confirmed, there are global offsets.
> >>
> >>
> >Actually, the GEOM provider goes though some gymnastics to portray the
offsets
> >as relative to userland, but ondisk they are still stored as absolute to
> >preserve compatiblity.
> >
> >
> You mean that "read mbroffset" to geom could return a relative value?
No, this is specific to the BSD label class, not something GEOM does in
general.
--
John Baldwin
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