Subject: EFI GPT and wedges/disklables on amd64 i386 and ia64
To: None <tech-misc@NetBSD.org>
From: Jonathan A. Kollasch <jakllsch@kollasch.net>
List: tech-misc
Date: 02/28/2006 23:54:10
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Hi,

 As there are now shipping EFI-based i386 machines, we should consider
how the partitioning will work on all the EFI machines.  Since EFI itself
may often need to read (and write) into at least one partition, a simple
disklabel-only scheme won't work.  Are wedges over the GPT[1] partitions
the way to go?  Or do we do a i386-like GPT+disklabel thing?  I believe
FreeBSD/ia64 is using a GPT-only scheme.

For starters the GPT partitioning program from FreeBSD should be ported
and imported.  It uses some FreeBSD-specific ioctls for determining
size of the disk, and I couldn't find an equivalent in NetBSD.  I'd be
willing to try to get it ported if I got some pointers in this area.

Also, for the GPT+disklabel possibility a gptlabel(8) program similar to
mbrlabel(8) may need to be written.  Or is a wedges-based system with only
the GPT on disk the way of the future?

	Jonathan Kollasch

[1] http://en.wikipedia.org/wiki/GUID_Partition_Table

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