[Info-vax] QIO Writes to a mailbox

[Steve Bainbridge]

On Nov 4, 2:46 pm, Steven Schweda <sms.antin... at gmail.com> wrote:
> On Nov 4, 5:04 am, Steve Bainbridge <stephen_bainbri... at yahoo.co.uk>
> wrote:
>
> > I have a very simple question, but when looking at the Alpha internals
> > manual and talking to colleagues the answer does not seem so obvious.
> > [...]
> > Unfortunately the writer does not check or report what value the IOSB
> > returns [...]
>
>    I'm confused.  You _know_ that you're ignoring the IOSB
> status, and, rather than fixing that, you're looking at "the
> Alpha internals manual"?  Really?
>
> > Is it QIO or QIOW? [...]
>
>    Another fair question.
>
>    Why not start by fixing the obvious problems, and then
> move on to the obscure stuff (if necessary)?

Hi,

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.

Whilst it's simple to change the code, replicating the problem has
proved impossible and releasing into production onto many tens of
systems takes a long time with a lot of effort - especially when we
don't know if the problem has been resolved. So we would prefer to try
and understand why we are seeing the problem, rather than just
incrementally trying to correct issues.

Steve