Config Q?: Preempt Model & Preempt Big Kern Lock

[Linda Walsh <lkml@tlinx.org>]

Not big deal, just some config-validity questions regarding
i386 preemption models and preemption of the big-kern lock.
I.e. the relevant options are:

(PM) "Preemption model", there are 3 choices (i386):
      (none) No Forced Preemption (Server)
      (vol) Voluntary Preempt (Desktop)
      (full) Preemptible Kernel (Low-Latency Desktop)
(PBL) "Preempt The Big Kernel Lock" (hint: use Y for desktop, else N)

===
Are these all "valid" config states?  Should they all be valid?

I.e., does it make sense to allow "PM==none && PBL==T" ?
Does it makes sense to allow "(PM==full) && PBL==F" ?

Is the issue of big-kernel-lock preemption of major consequence
these days, or should it work in all cases?  Are there cases
where one might want PBL==F?  Would they be limited to the
"PM=none" case?

Is this the right place or way to ask such questions, or to
get information?

In asking a similar information question, it seems that it
was preferred that a bug be filed.  Is that the case here?

Thanks,
Lin