== Some notes on booting single user in x86 Solaris 10

Here's some somewhat sketchy notes, mostly for my own future reference,
on various bits of booting Solaris 10 x86 into single-user mode.

On x86 Solaris, kernel boot parameters go on the end of the '_kernel
/platform/i86pc/multiboot_' line in the GRUB boot entry. You put them in
by interrupting the GRUB menu to edit the default boot entry (and then
that line).  The two most useful parameters are _-s_ for single-user
boots and _-v_ to dump kernel messages to the screen as the system boots
instead of just to syslog.

However, this single user isn't really completely single-user, because
there are still a bunch of _svcs_ things that get started and run.  It
is [[possible for some of these to crash ClearingMetadbs]], leaving you
with a machine that will not come up even when booted with _-s_.

(You cannot fix this by booting the rescue environment, because you
can't use it to turn services off in your regular system; the _svcs_
framework has to be running before you can do things like _svcadm
disable_ errant startup bits.)

In this situation, boot with '_-m milestone=none_'; this starts
the _svcs_ framework but runs almost nothing. In particular, the
root filesystem is not mounted read-write; you can either run
_/lib/svc/method/fs-root_ or do it by hand with

>  fsck /
>  mount -o remount,rw /

(you will also need to mount _/usr_ and so on if applicable.)

At this point you can use _svcs_ and _svcadm_ to modify what will
be run, for example to force off svc:/system/metainit. An important
safety tip: under at least some situations, trying to _svcadm disable_
an already disabled service will cause _svcadm_ to just give you its
general usage message instead of explaining what's actually wrong.

(It is possible to spend some time retyping command lines very carefully,
trying to figure out just what stray bit snuck in, before the penny
drops. Fortunately I was experimenting, not in the middle of a crisis.)

Useful information is in _/lib/svc/share/README_ aka [[here
http://www.sun.com/msg/SMF-8000-QD]], and the various scripts that are
run to start things are in _/lib/svc/method/_.

(Probably all the hip _svcs_ people already know that, but I didn't.)