GPT - (last) call for action

Ivan Voras ivoras at
Sat Jun 9 16:23:30 UTC 2007


I think I might be getting boring with pushing this idea so I intend
this to be my last broadcast about it.

The idea is: to replace old "MSDOS fdisk"+"BSD labels" partitioning
scheme with GPT partitions. The old scheme is a not-really-clean hack
and the major issue with it is that it can't support partitions larger
than 2 TB (and also storage devices larger than 2 TB).

The 7.0 release is ideal for this, since it will deliver many nice
things, such as ZFS, gjournal, and also, among others, a new installer
( - hence my interest in this).

The support for GPT is incomplete: the major thing missing is the
capability to boot from GPT-partitioned system (assuming there's no EFI
firmware - meaning we're interested in plain x86/amd64 systems). Almost
all of the boot loader chain (mbr, boot0, boot1, loader) will have to be
modified, but not all of it extensively. One solution would be to have
separate chains for fdisk+bsdlabels and GPT booting. Implementing all
this on non-EFI systems might require violating the EFI/GPT spec a little.

Another thing that would be nice to have is support for fdisk and
disklabel partitions inside geom_part, so it's management utility can be
used for both GPT and old style partition management (instead of
currently used two tools: fdisk and disklabel).

Since 7.x will be branched soon-ish, this modifications will have to be
done soon, or the 7.x branch will continue to use old style partitions.

While the consensus is that GPT and GEOM_PART are very nice and
desirable instead of the current scheme (which is really obsolete now
and will soon become useless on even medium-sized machines), AFAIK
nobody's offered to do it, and this is a sort of call for volunteers.

There's more info in the hackers@ archives, and for those interested,
general description of GPT can be found at:

The actual specification of GPT is a part of the EFI specification

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