Re: DEQNA doc inconsistency

[Johnny Billquist <bqt%update.uu.se@localhost>]

On 2020-08-18 04:05, Mouse wrote:
> I was reading a PDF of - or, let me precise, supposedly of -
> EK-DEQNA-UG-001, the DEQNA "user's guide" (which includes programming
> doc).  It looks like a scan of a paper copy.
>
> But I see an inconsistency in it.  In receive descriptors, in the first
> status word, page 58 of the PDF, page 4-9 in internal page numbering,
> says that bit 12 is
>
> 	DISCARD.  When set, indicates that OVF (bit 00), CRCERR (bit
> 	01), and SHORT (bit 03) are valid (that is, they pertain to
> 	this packet).  This bit is never set unless one of the other
> 	three bits is set.  Sets bit 14.
>
> But the next page says that bits 07:03 are reserved.  And bit 2 is
> called FRAME, so it's not just a typo in the bit number for SHORT.
>
> if_qereg.h defines both QE_FRAME and QE_SHORT, but if_qe.c doesn't use
> either one as far as I can see.  Interestingly, there is a comment on
> QE_SHORT giving a semantic for it, one which as far as I can see is not
> supported by EK-DEQNA-UG-001, and the file has a DEC copyright and
> license notice, so I am inclined to suspect that it may know better
> than the PDF.
>
> I don't suppose anyone here knows what the real story is?

I don't know the real story, but I can tell that RSX also knows about 
the short flag, which is bit 3. Seems either DEC forgot to document it, 
or they tried to remove the documentation of it.

Looking at the DELQA, the whole DISCARD bit was removed, as was any 
reference to the SHORT bit.

In the RSX DECnet DEQNA driver, there is a check if the DISCARD is set, 
and if so, they clear out the SHORT before deciding if there is 
something to log. If only the SHORT bit was set, the packet is just 
discarded, if something else is set, it goes to the error log.

But that is the only thing related to the SHORT bit I could find.

  Johnny

--
Johnny Billquist                  || "I'm on a bus
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