booting from a hdd image

For some reason during a HDD boot, SCSI disk driver (sd) is loaded before SCSI controller's (esp) . So the system can find no disks and exits causing kernel panic:

Cannot assemble drivers for root /iommu@0,10000000/sbus@0,10001000/espdma@5,8400000/esp@5,8800000/sd@0,0:a
Cannot mount root on /iommu@0,10000000/sbus@0,10001000/espdma@5,8400000/esp@5,8800000/sd@0,0:a fstype ufs
panic: vfs_mountroot: cannot mount root

A workaround: add the following line to /etc/system in the HDD image:
set scsi_options=0x58

Updated the Solaris/sparc under qemu how-to.