Modern OpenSolaris is configured to disallow root logins during normal boots. It is only possible in single-user mode. However, many instructions online simply say to add "-s" to the end of the default grub boot arguments, which leaves a graphical boot progress display in an endless loop and never enters the single-user mode console.
The key point left out of many OpenSolaris single-user boot instructions is that you must modify a text boot grub entry, and not the default graphical entry. Booting in graphical mode with the single-user switch leaves the boot progress graphic overlayed atop the console forever, never allowing the maintenance console to be visible.
text boot
entry and press 'e
'.kernel$
and press 'e
'.-s
' to the end of the line.e.g. change:
kernel$ /platform/i86pc/kernel/$ISADIR/unix -Bv$ZFS-BOOTFS
to
kernel$ /platform/i86pc/kernel/$ISADIR/unix -Bv$ZFS-BOOTFS -s
enter
'.b
' to boot.The system should boot without a graphical overlay, and should promptly arrive at the system maintenance console.