DragonflyBSD GEOM? (Re: Is it time to dump disklabel and use GPT instead?)
dillon at apollo.backplane.com
Thu Jul 29 18:04:48 PDT 2010
:> If someone wants to write a really nice gpt partition editor that
:> pops you into vi or emacs or whatever then I would be more amendable
:> to using gpt as a default. But if all we have is command-line
:> list/add/remove junk, then no.
:Can you give me some pointers as for where to start looking for more
:information on our implementation of GPT? How much low level stuff is
:involved in writing such an editor?
The kernel understands gpt partitions. The boot code does not.
The userland tools are the old FreeBSD tools, in /usr/src/sbin/gpt.
GPT based projects can be broken down as follows:
For the gpt tool:
* Add an editor feature to the gpt tool that lays out existing
partitions and allows new ones to be specified, similar to
how disklabel -e works now.
* Implement super sector alignment and implement silent skipping
of the small gap areas created between partitions when super sector
alignment is done.
For the boot code:
gpt with a compat mbr replaces fdisk entirely. Add a version of
the boot0 code that can find the boot partition. Another option
here is to hardwire the offset in and have gpt figure it out and
update it in-place, which might be needed for boot0.
A gtp-aware boot1/boot2 is then needed, and probably also a
I expect a good chunk of this could be ported from FreeBSD.
For native GPT booting (non compat MBR booting) ... I don't know much
about that, but it would be a separate sub-project.
<dillon at backplane.com>
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