NanoBSD: support for GPT partitioning

[thomas]

Summary

This change introduces a new variable NANO_PART_SCHEME, which can be used to
specify the desired partitioning scheme. The default is "MBR", providing a
legacy PC partition table, for backwards compatibility.

The alternate value "GPT" causes a GPT partitioning to be used instead. The
two system slices are p1 and p2. The configuration slice is p3. An additional
boot slice p15 is created to hold the GPT boot code.

Test Plan

Tested with the "rescue_amd64" configuration

[imp]

This is a good start, but I think needs some cleanup.

Also, I have a bunch of patches to use mkimage which doesn't require root at all, as well as brook's NO_ROOT stuff to build the mtree files that makefs can use to populate the whole tree. These patches are incomplete at this time, but is more in the direction I'd hoped to go. How does that fit with what you've done?

tools/tools/nanobsd/defaults.sh

425

Why not have
CFG_PART=s3 # for MBR
or
CFG_PART=p3 # for GPT
CFG_DEV=${NANO_DRIVE}${CFG_PART}

and use that here:

echo "mount -o ro /dev/${CFG_DEV}" > conf/default/etc/remount

With similar for the other partitions / slices we used to use...

530

Won't gpart do all this math now so we don't need to? And can't we just call gpart directly to do it?

613–623

I thought gpart was able to do this too, w/o needing to resort to bsdlabel at all.

[thomas]

Thanks for your feedback, Warner! I will send an updated patch.

[emaste]

Still working on this?