[Info-vax] Pointless Nostalgia: System Service Dispatching

[Johnny Billquist]

On 2016-06-30 18:55, VAXman- at SendSpamHere.ORG wrote:
> In article <nl3491$rou$1 at Iltempo.Update.UU.SE>, Johnny Billquist <bqt at softjar.se> writes:
>> On 2016-06-30 01:05, lawrencedo99 at gmail.com wrote:
>>> On Wednesday, June 29, 2016 at 11:36:10 PM UTC+12, Johnny Billquist wrote:
>>>> Consider a $QIOW for example. If you get an AST, you do not want the $QIOW
>>>> to be reexecuted.
>>>
>>> That’s not a problem, because there is no actual $QIOW system call.
>>
>> There isn't? Did I place the $ on the wrong side or something now? Or
>> what are you suggesting?
>
> SYS$QIOW => SYS$QIO+SYS$SYNCH

Functionally, yes. But does it actually put two different syscalls in 
your instruction stream, one after the other?

On RSX, QIO$ and QIOW$ are two different DICs, even though QIOW$ really 
is the same as a QIO$ followed by a WTEF$

Looking on a VMS system, it's a bit unclear. The $QIO_S and $QIOW_S 
calls different functions. But what those functions do, in turn, I don't 
know. (SYS$QIO and SYS$QIOW)

	Johnny