Article 4857 of vmsnet.internals:
In comp.os.vms Eric F. Richards <efricha@flatland.dimensional.com> wrote:
> Greetings all...

> I'm trying to figure out something in the lock manager.

> What I want to do is create a lock in EXEC mode and be able to convert it
> in USER mode.  Now, the impression I get from the docs is that I can do
> this, if I say, for example

>         $enqw_s lkmode=#lck$k_nlmode, -         ; create a null lock
>                 acmode=#psl$c_user, -           ; ...user-mode,
>                 resnam=name, -                  ; ...using this name
>                 lksb=lksb                       ; store its lock ID here

> to create the lock, and then from user mode, say...

>         $enqw_s lkmode=#lck$k_exmode, -         ; convert lock to exclusive
>                 flags=#lck$m_convert, -         ; ...
>                 acmode=#psl$c_user, -           ; ...user-mode,
>                 lksb=lksb                       ; this is the ID

> However, this returns SS$_IVLOCKID.  So...

> 1) is there a way to do what I want, that is, create the lock in an elvated
>    processor mode and convert it at USER mode?

Brian Schenkenberger sent me a short hack to get around this problem,
basically by modifying the LKB after the fact.  It seems to behave
exactly the way I want it to:

	$cmkrnl_s routin=fixit			; always legal from EXEC mode
	blbc	r0, error			; on error bail out

. . .

	.entry	fixit, ^m<r4, r6>		; R4 get LKID, R6 gets LKB addr
	movl	lksb+4, r4			; get lock ID
	jsb	g^lck$validate_local_lkid	; get LKB
	blbc	r0, 10$				; on error bail out
	insv	#psl$c_user, #lkb$v_mode, -	; set lock mode to USER mode
		#lkb$s_mode, lkb$b_rmod(r6)	; ...in LKB -- just force it.
10$:	ret					; back to EXEC mode

-- 
Eric F. Richards
efricha@alumni.cs.colorado.edu
"The weird part is that I can feel productive even when I'm doomed."
 - Dilbert