Boot from btrfs RAID5/6?

I'm trying to build an Arch Linux system with a btrfs RAID5/6 root. When I install GRUB on one of the volume's disks, it prints a message like this on startup:

error: no such device: [my btrfs volume uuid]

…and then dumps me into a recovery shell. If I type ls (hdX) (where X is one of the volume's physical disks, it prints some error text including this:

Unsupported raid flags 82

A few forum threads suggest that GRUB doesn't doesn't support these kinds of btrfs volumes right now. So, my next thought was to create a separate ext4-formatted boot drive. I started from an Arch live CD and did this:

$ mount /dev/sdb /mnt # one of the btrfs RAID5 disks
$ arch-chroot /mnt/root /bin/bash
$ mkfs.ext4 /dev/sdi # our new boot disk
$ mount /dev/sdi /mnt # /mnt inside the chroot
$ grub-install --target=i386-pc --root-directory=/mnt /dev/sdi
$ grub-mkconfig -o /mnt/boot/grub/grub.cfg
$ umount /mnt
$ exit # …the chroot
$ reboot # …and switch the boot drive in BIOS settings

I successfully landed in GRUB, but got these messages after the menu timeout:

error: no such device: [my btrfs volume uuid]
Loading Linux linux ...
error: hd6 cannot get C/H/S values.
Loading initial ramdisk ...
error: you need to load the keel first.

Press any key to continue...

…then I was dumped back into the GRUB menu. I'm trying to find answers to two questions:

1. Am I doing something wrong in creating my bootstrap volume?
2. Is there another, better way to boot my system from the btrfs RAID?

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