The failsafe boot environment is great, but sometimes you just need good old single-user. (Or whatever fancy name it has now SMF runs the show.)

When you get the boot menu, select your normal Solaris BE, and hit e. With the cursors, highlight the kernel line, then press e again and add your -s at the end, with a carriage return, an you’ll have something like:

findroot(pool_rpool,0,a)
kernel$ /platform/i86pc/multiboot -B $ZFS_BOOTFS -s
module /platform/i86pc/boot_archive

Obviously, the exact information might vary, depending on your boot device, and if you’re using ZFS root, but you get the idea.

Now hit b and it’ll boot to the single-user milestone.

So far as I can tell, you can add any of the standard Solaris boot options in there. -v is probably the most interesting, especially if you’re not entirely up-to-date on how SMF handles the boot process.