GPT and raidframe aware bootstrap

Hello

After some frustration booting off raidframe based filesystem larger
than 2 TB [1], I worked on x86 bootstrap to make it fully GPT and
raidframe aware. The goal is to be able to boot off partitions defined
by a GPT inside a RAID1 raidframe set. 

While there I added the ability to use raidframe device names and GPT
label names in the bootstrap; with the idea that it helps making
boot.cfg files that are stable when disks are added or removed.

Here is the patch for review and feedback:
ftp://ftp.netbsd.org/pub/NetBSD/misc/manu/raidgpt5.patch

Here are a examples of dev command output on a few testing setups:

1) A raidframe with a GPT inside. raid9 appears in the available
devices, and the GPT partition in contains appear with their label. One
can boot NAME=root@raid8:/netbsd 
> dev
disk hd0 size 1024 MB
  hd0a(4.2BSD) hd0e(RAID)
disk fd0
  fd0a
disk fd1
  fd1a
raidframe raid9 serial 20190807 in hd0e size 535 MB
  NAME=root@raid8(NetBSD FFS) NAME=scratch@raid8(NetBSD FFS, bootme)
default hd0e

2) A raidframe with a disklabel (no GPT), We support raid9a:/netbsd
> dev
disk hd0 size 1024 MB
  hd0e(RAID)
disk fd0
  fd0a
disk fd1
  fd1a
raidframe raid9 serial 20190918 in hd0e size 1023 MB
  raid9a(4.2BSD) raid9b(swap) raid9e(4.2BSD)
default hd0e

3) EFI boot with a GPT that has a raidframe partition and a GPT inside
the raidframe. Here we can use boot NAME=root@qemu:/netbsd 
> dev
disk hd0 mediaId 0 size 1024 MB
  NAME=efi@qemu(EFI System) NAME=ffs@qemu(NetBSD FFS)
  NAME=raid9@qemu(NetBSD RAID)
raidframe raid9 serial 20190730 in NAME=raid9@qemu size 383 MB
  NAME=root@qemu(NetBSD FFS) NAME=scratch@qemu(NetBSD FFS, bootme)

In the three examples, booting the RAID device itself is possible (boot
hd0e or  NAME=raid9@qemu in last example). This will use the first
partition in the RAID, or the partition that has the bootme attribute.

[1] http://mail-index.netbsd.org/netbsd-users/2019/07/25/msg023215.html

-- 
Emmanuel Dreyfus
http://hcpnet.free.fr/pubz
[email protected]