Re: [9fans] Re: [explanations] MBR messed up on installation

["Paweł Lasek" <pawel.lasek@gmail.com>]

On 5/28/07, tlaronde@polynum.com <tlaronde@polynum.com> wrote:
> Hello,
[cut]
> TODO: track the Plan 9 sources to see the manipulation done.
> Found where the hardware description is obtained (for the ATA CHS
> values at least).
> Problem of portability (this is i386 specific).
> Why is fdisk(8) recomputing the absolute sector to put it in a BIOS
> cylinder boundary (that has almost no sense). And why does it redefines
> the starting sector of a partition it has neither created nor modified
> (for the geometry). It seems that this is modified when setting the
> ACTIVE flag, that is all the record is overwritten, including recomputed
> CHS and LBA values.

At the moment, fdisk also redefines partition numbers, rearranging
them as it finds them on the disk (So if you have first partition
number 3, then number 1, then number 2, it gets changed to 1-2-3).

It would be a fine thing if Plan 9's fdisk would rather follow the way
of GNU/BSD fdisk and _NOT_ touch any partition it didn't modify. While
the usage of plan 9 named partitions makes it irrevelant to p9, many
people have other OS on their hard drive which don't add another layer
(like disklabel or LVM) or aren't configured to do so.

Booting another OS just to run fdisk isn't a good thing. Pity that I
don't have access to a Plan 9 machine (or time) to prepare a patch for
this :-/

> To be continued.
> --
> Thierry Laronde (Alceste) <tlaronde +AT+ polynum +dot+ com>
>                  http://www.kergis.com/
> Key fingerprint = 0FF7 E906 FBAF FE95 FD89  250D 52B1 AE95 6006 F40C
>

-- 
Paul Lasek