Languages SIG Meeting

Dan Oldman <oldman@DG-RTP.DG.COM>
Wed, 12 Sep 90 15:04:28 edt

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Languages SIG Meeting oldman@DG-RTP.DG.COM (Dan Oldman) (1990-09-12)
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Newsgroups: comp.compilers
From: Dan Oldman <oldman@DG-RTP.DG.COM>
Keywords: report
Organization: Compilers Central
Date: Wed, 12 Sep 90 15:04:28 edt



The first meeting of the UNIX System V Programming Language SIG

September 27th and 28th 1990, Westboro, Mass.

This is the second announcement of the organization of a Special Interest
Group that is concerned with programming language support in UNIX System V.
Response from the first announcement has been good (22 expressed interest in
attending and another 34 want to be involved electronically) and we are about
to hold an organizational meeting. I'm sorry for the short notice, but you
were warned about it in the first announcement. The meeting is structured
into an initial day of somewhat freewheeling technical discussion to get to
know each other and get a better sense of what can and should be
accomplished, followed by a half a day of more mundane organizational
details. Here's the agenda for the meeting:

Thursday September 27, 1990
      8:30 Breakfast buffet - get acquainted
      9:30 Welcome and introductions (Dan Oldman)
    10:30 Break
    10:45 Potential issues to be worked on in this SIG
Debugging information
Shared library RTLD interfaces (user and debugger)
Kernel debugging interfaces
Format of core files (shared library issues)
Support for the long long type in C
Language issues in support of threads
Performance measurement
profiling noncontiguous address spaces
other ideas?
Debugging optimized code
Needs of supercomputers?
    12:00 Lunch (Provided by Data General)
      1:00 Debugging information
What languages should be supported?
What does support mean?
Design goals
Existing technologies (COFF, BSD, DWARF,...)
Reasonable alternatives (DWARF, DWARF+, BSD?, ??)
      3:00 Break (beverages & cookies)
      3:15 Debugging information (continued)
Levels of abstraction
Objects & attributes
Binary encoding
Symbolic (assembly) language
Programmatic interface
Mapping from specific programming languages
Where do we go from here?
      5:00 Break for the day

Friday September 28, 1990
      9:00 Charter discussion
Relationship with standards organizations
Potential officers
chairman, co-chairman, secretary
Term of office
Frequency of meetings and alternatives
email, conference calls
Voting - desire consensus
Reporting - minutes and reports
Uses and distribution of any mailing lists
Mailing list names and administration
    10:30 Break (coffee & rolls)
    10:45 Administrivia
Election of officers
Action items
Next agenda
Next (and other) meeting locations
      1:00 Good-bye

The meeting will be held at:

      Data General Corporation
      The Executive Briefing Center
      3400 Computer Drive
      Westboro, Mass.

      (Maps and directions available upon request.)

A block of rooms has been reserved at:

      Westboro Marriott
      5400 Computer Drive,
      Westboro, MA 01581

They have guaranteed a rate of $99 (plus 9.7% tax, single or double
occupancy) if you reserve by September 18th. This hotel is a short walk to
the DG Executive Briefing Center. When reserving, tell them you are a member
of the "UNIX Languages Group".

Transportation between Boston's Logan Airport and the hotel can be arranged

      Knight's Airport Limousine Service, Inc.
      1-800-227-7005 (Massachusetts only)

If you wish to attend, please respond before Thursday, September 20th, via
email, fax, mail, or phone with the information requested below. That way I
can order enough food. If you are already on my mailing list, then skip the
information you already sent. I will acknowledge any messages that you send
me to guard against things being lost in the mail and send you specific
directions to get to the meeting.

      Areas of interest:
      Phone number:
      Fax number:
      Email address:
      Mail address:
      Level of interest:
      __ I will attend the September 27th & 28th meeting.
      __ I can't come but want to actively monitor email discussions.
      __ I am interested in occasional status reports.


For those of you who missed the first announcement, here's a bit more
background material taken from the first announcement.
Announcing the formation of a UNIX International Special Interest Group on
Programming Language Issues. This group will act as a clearing house for UI
member companies and other interested parties to resolve issues of supporting
various programming languages on UNIX System V. One pressing problem is the
support of debugging.

Debugging Support

One significant change introduced by System V Release 4 is the replacement of
COFF (Common Object File Format) with ELF (Executable and Linker Format)
representation of programs. COFF, despite many problems, had a barely
acceptable but functional representation for debugging information. ELF, at
this time, lacks anything but the suggestion that the .debug section might
contain some debugging information. There is also only a weak standard in the
area of debugger interface to the kernel.

The lack of a standard is a serious impediment to third party compiler
writers who wish to work with the standard system debugger and with third
party debugger writers that wish to operate on many UNIX platforms with
standard and third party compilers. Any programmer who wishes to debug an
application that is built with two or more different compilers is also hurt
by the lack of a standard.

Attempting to develop standards in this area is not new. The needs of the
popular programming languages and debuggers are substantial and past attempts
have ended with the current situation of "agreeing to disagree". This ignores
the fact that the 80-20 rule applies well here. We can solve the needs of 80%
of the community with 20% of the work. If we design extensibility into the
standard, the remaining 20% of the community can build on top of the standard
and get more done with less effort.

UNIX Software Labs has developed a new debugger representation, called DWARF,
that is used in SVR4 C Issue 5 compiler and SDB debugger. It has some of the
qualities of an acceptable standard and would probably be a good place to

Goals of the SIG

As stated earlier, the overall goal of the SIG is to provide a clearing house
for UI member companies and anyone else who has an interest to resolve
programming language support related issues on UNIX System V. There are some
specific projects that the SIG must complete as soon as possible:

          1. Develop a robust and efficient framework for debugging information.
This framework will consist of a generic base that deals with the
common problems of the popular third generation languages and
supports extensibility for other uses.

          2. Define how the following languages map onto this framework: C (K&R
and ANSI), Fortran (77 and 90), C++, and probably others.

          3. Define the format of "core" files.

          4. Define the interface between the debugger and the RTLD (shared
library runtime loader).

          5. Define a standard for Kernel support of debugging and then extend
that standard to deal with upcoming features like threads.

Beyond that there are other issues that could be standardized such as support
for debugging in the absence of debugger information and support for long
long integer types. I'm sure that there are more things that I have not
mentioned here.

Thank you for your interest.
Dan Oldman internet:
Data General Corporation uucp: ...!mcnc!rti!dg-rtp!oldman
62 Alexander Drive voice: (919) 248-6125
Research Triangle Park, NC 27709 fax: (919) 541-9089

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