[Info-vax] QIO Writes to a mailbox

[Steve Bainbridge]

On Nov 4, 8:52 pm, VAXman-  @SendSpamHere.ORG wrote:
> In article <j91ebq$fb... at pcls6.std.com>, moro... at world.std.spaamtrap.com (Michael Moroney) writes:
> >Steve Bainbridge <stephen_bainbri... at yahoo.co.uk> writes:
>
> >>This code was written several years ago and I've been dumped on to
> >>investigate and correct the issue we now very occasionally see. I'm
> >>aware of the obvious missing check on the IOSB, but I can't say with
> >>any certainty that this is causing the problem.
>
> >You *must* check the IOSB status and make sure the operation is complete
> >to ensure the operation was performed properly.  Especially when using
> >QIO (no W).
>
> Exactly.  However, he hasn't yet indicated where the IOSBs are allocated.
> If it is on the stack in that routine invoking the $QIO or in any routine
> calling it, all bets are off if that routine returns BEFORE the $QIO has
> completed -- even if he DOES check the "IOSB".
>
> >Not checking the status is almost certainly the cause of the problem.
>
> Hey, but he's a C coder.  They dun't need no steenkin status checking.
> I've found asynchronicity a foreign concept to the average unix mind.
> --
> VAXman- A Bored Certified VMS Kernel Mode Hacker    VAXman(at)TMESIS(dot)ORG
>
> All your spirit rack abuses, come to haunt you back by day.
> All your Byzantine excuses, given time, given you away.

VAXman,

I'm aware of your love of the C language, but just down another pint
of the black stuff and calm down.

As I said at the beginning of this thread the IOSB is never checked,
so we don't know if and why the QIO completed OK - I am only trying to
find reasons why it would not - given the limited information
available to me (the IOSB is declared as a static variable at the
beginning of the procedure)

Steve