Howto setup multiboot with GPT?

[Andrey V. Elsukov]

Hi,

I have installed 8.0-BETA2 amd64 on ZFS root with GPT. I made addition partition and
made new ZFS pool, builded and installed i386 world and kernel to this pool. 
So, is there some way to select from which partition i want to boot?

My configuration:
> gpart show ad10
=>        34  1250263661  ad10  GPT  (596G)
          34         256     1  freebsd-boot  (128K)
         290     8388608     2  freebsd-swap  (4.0G)
     8388898   209715200     3  freebsd-zfs  (100G)
   218104098   209715200     4  freebsd-zfs  (100G)
   427819298   822444397        - free -  (392G)

> zpool list
NAME    SIZE   USED  AVAIL    CAP  HEALTH  ALTROOT
amd64  99,5G  10,5G  89,0G    10%  ONLINE  -
x86    99,5G   346M  99,2G     0%  ONLINE  /mnt

> cat /boot/loader.conf 
zfs_load="YES"
vfs.root.mountfrom="zfs:amd64"
> zfs list -r amd64
NAME              USED  AVAIL  REFER  MOUNTPOINT
amd64            10,5G  87,5G   511M  legacy
amd64/distfiles  1,10G  87,5G  1,10G  /usr/ports/distfiles
amd64/home       4,29G  87,5G  4,26G  /usr/home
amd64/local      1,91G  87,5G  1,91G  /usr/local
amd64/obj        1,29G  87,5G  1,29G  /usr/obj
amd64/ports       162M  87,5G   162M  /usr/ports
amd64/src         405M  87,5G   405M  /usr/src
amd64/tmp        26,7M  87,5G  4,96M  /tmp
amd64/usr         263M  87,5G   263M  /usr
amd64/var         532M  87,5G   524K  /var
amd64/var/crash   411M  87,5G   411M  /var/crash
amd64/var/db      120M  87,5G   120M  /var/db
amd64/var/tmp     112K  87,5G    79K  /var/tmp

> zfs list -r x86
NAME            USED  AVAIL  REFER  MOUNTPOINT
x86             346M  97,6G   170M  legacy
x86/local        18K  97,6G    18K  /mnt/usr/local
x86/tmp          23K  97,6G    23K  /mnt/tmp
x86/usr         175M  97,6G   175M  /mnt/usr
x86/var         241K  97,6G   178K  /mnt/var
x86/var/crash  18,5K  97,6G  18,5K  /mnt/var/crash
x86/var/db       25K  97,6G    25K  /mnt/var/db
x86/var/tmp      19K  97,6G    19K  /mnt/var/tmp

-- 
WBR, Andrey V. Elsukov