when does kill -9 pid not work?

[Jerry M. Denman]

In article <9748 at alice.UUCP> debra at alice.UUCP () writes:
>In article <20495 at adm.BRL.MIL> Leisner.Henr at xerox.com (Marty) writes:
>}I had an infinite loop in my boot loader, and I couldn't kill the DOS task
>}via a
>}kill -9 pid
>
>kill -9 pid (executed as the owner of the process or as root) is
>guaranteed to work.
>

I would have to differ in opinion on that answer.  According to Bach, 
if a process gets "hung" while in kernal mode, there is no way to kill
it.  This is to prevent corruption of the kernal tables.  If a process is
in any other mode besides kernal, then a kill -9 will terminate it.  The 
most common example of this is if you hang a device driver.  They spend
a greater share of the time executing kernal level tasks and do tend to 
drop off into never never land without notice.  Many times when this happens
a reboot is the only way to clear the process from the table.

Of course, I have been know to be wrong.