grsecurity

I've been trying to get a custom kernel to boot. I can compile and boot a vanilla 2.6.28 kernel, but when I use gentoo's hardened kernel which has PaX and grsecurity, it fails, even if I use an identical kernel config to the vanila kernel.

When booting it fails immediatly from pv_grub with

  Booting 'Gentoo kernel-2.6.28-hardened-r9'

root (hd0)
 Filesystem type is ext2fs, using whole disk
kernel /boot/kernel-2.6.28-hardened-r9 root=/dev/xvda

close blk: backend at /local/domain/0/backend/vbd/315/51712
close blk: backend at /local/domain/0/backend/vbd/315/51728

This is on a 64bit linode system and obviosuly using pv_opts

Any ideas?