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 5-Jan-88 16:23:20-PST,2148;000000000005
Return-Path: <SRA@XX.LCS.MIT.EDU>
Received: from XX.LCS.MIT.EDU by SRI-NIC.ARPA with TCP; Tue 5 Jan 88 16:23:13-PST
Date: Tue 5 Jan 88 19:22:34-EST
From: Rob Austein <SRA@XX.LCS.MIT.EDU>
Subject: Re: PSECT support for KCC
To: KLH@SRI-NIC.ARPA
cc: Bug-KCC@SRI-NIC.ARPA, MRC@XX.LCS.MIT.EDU
In-Reply-To: <12364283106.28.KLH@SRI-NIC.ARPA>
Message-ID: <12364288013.49.SRA@XX.LCS.MIT.EDU>

The files are in XX:<SRA.77>.  You want CPSECT.MAC (sic), CENDPS.C,
and CRT.C.

My interest in being compatable with existing MACRO libraries stems
from extreme frustration at trying to keep parallel versions
consistant when we have a perfectly good linking loader that's
supposed to be able to solve all these problems for us.  I want the C
code (which will be installed, on XX anyway, as C:LIBsomething.REL) to
be able to load whatever the current latest and greatest HSTNAM.REL
is, straight out of the MMAILR distribution.  The C code will just be
something to translate between calling conventions.  Or I might even
just write a single routine that translates between the normal MACRO
calling conventions (args/vals in AC1->AC4, +1/+2 return) and C
conventions, sort of like jsys().  Reimplementing the same code in
multiple languages is a huge waste of time that I can't afford.

I agree that making extended .EXEs directly would be nice.  The CRT changes
should free you from some of the LINK randomness; the only JOBDAT symbol
used by the PSECT version is .JBSA, and that's only used so that we can
safely include the symbol table at the end of the code segment.

There shouldn't be any problem with handling this stuff like -i, that's
why the modules are set up as they are.  Nor should there be any problem
with using FAIL for user modules, although I can't see why anyone would
want to (I know, ancient history).  All the static data and code
still fits in a single section; in fact, the only difference in the
memory layout in my initial version of the PSECT code is that
the low segment begins at 1000 instead of 140 so that the DATA
psect can start on a page boundry (LINK gets -very- upset otherwise).
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 7-Mar-88 22:11:17-PST,1730;000000000015
Return-Path: <SRA@XX.LCS.MIT.EDU>
Received: from XX.LCS.MIT.EDU by SRI-NIC.ARPA with TCP; Mon 7 Mar 88 22:11:11-PST
Date: Tue, 8 Mar 1988  01:10 EST
Message-ID: <SRA.12380604295.BABYL@XX.LCS.MIT.EDU>
From: Rob Austein <SRA@XX.LCS.MIT.EDU>
To:   Ken Harrenstien <KLH@SRI-NIC.ARPA>
Cc:   sra@XX.LCS.MIT.EDU
Subject: PSECT support
In-reply-to: Msg of 7 Mar 1988  23:25-EST from Ken Harrenstien <KLH@SRI-NIC.ARPA>

/REDIRECT is documented at least minimally in the v6 HLP:LINK.HLP.
There's a copy of this on XX if it's not on NIC.

Everything in CPSECT.MAC can be done trivially by LINK switches with
one exception: I don't think LINK supports any way of making the code
PSECT read-only via LINK switches.  I suppose this is not vital, but
it would certainly be a nice feature to be able to use for debugging.
This is a general-purpose feature missing from LINK, not KCC specific,
so it might be reasonable to distribute a LINK source patch and some
conditionalized code in KCC to use it, for sites that want it.  Or
maybe DEC has fixed this since the last time I read the documentation,
although I doubt it.

If you think you can do the CENDPS stuff via PDVs, great.  I've never
tried to use PDVs for anything.  I certainly have no attachment to the
current method, other than that it works.  I don't think there is any
way to cleanly define the end-of-psect symbols from LINK command level
without resorting to really nasty kludgery.

The .HBHSP test was derived empiricly, obviously DEC could break it in
the next version of LINK they release.  All I can say is that it seems
to work and that the only other method I could think of to determine
PSECTness was to grovel the symbol table at runtime.
 7-Mar-88 20:25:56-PST,1765;000000000001
Mail-From: KLH created at  7-Mar-88 20:25:54
Date: Mon, 7 Mar 88 20:25:54 PST
From: Ken Harrenstien <KLH@SRI-NIC.ARPA>
Subject: PSECT support
To: sra@XX.LCS.MIT.EDU
cc: klh@SRI-NIC.ARPA
Message-ID: <12380585238.50.KLH@SRI-NIC.ARPA>

OK, I have a little time now, and have cleaned up KCC for distribution
with the exception of possibly adding PSECT support.  What I'd like to
do is remove the need for CPSECT, and possibly CENDPS as well, by
telling KCC to invoke LINK with the appropriate arcane switches.

It's been a long-time problem trying to set things up so that the
COMPIL class commands for COMPILE, LOAD, etc. will work properly.
I've more or less given up on this and now use KCC itself as the
front-end to LINK; at the cost of losing the COMPILE generality,
everything else becomes much simpler (and more homelike for Unix fans,
if that helps any).  Of course if one were willing to hack the EXEC
and LINK to know about KCC specially, the way they already do for
other things like FORTRAN, anything is possible.  But that isn't a
realistic alternative.

I'm pretty sure that KCC can take care of the stuff that CPSECT is
currently doing.  The problem is, my LINK manual is dated March 1983
and doesn't contain things like /REDIRECT.  I'm trying to dig up a
more recent one, but don't know yet whether we have one lying around.

As for CENDPS, I was thinking that CRT.C could use the PDV to
determine where things are at runtime; alternatively KCC could define
the end-symbols using switches, if there is any way to query LINK on
the current value of its location counters.

Including the changes to CRT.C is no problem, as long as that
.JBHSP test is guaranteed to distinguish the PSECT case.

Any thoughts?
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 8-Mar-88 12:06:29-PST,450;000000000001
Mail-From: KLH created at  8-Mar-88 11:44:16
Date: Tue, 8 Mar 88 11:44:15 PST
From: Ken Harrenstien <KLH@SRI-NIC.ARPA>
Subject: Re: PSECT support
To: SRA@XX.LCS.MIT.EDU
cc: KLH@SRI-NIC.ARPA
In-Reply-To: <SRA.12380604295.BABYL@XX.LCS.MIT.EDU>
Message-ID: <12380752419.50.KLH@SRI-NIC.ARPA>

Thanks!  I'll let you know if I uncover anything myself.  Boy, I hate
messing with LINK!  I'm impressed you managed to get anything to work.
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