Platforms using COFF?

Platforms using COFF?

[Eli Zaretskii]

I'm sorry for posting a slightly off-topic question, but I think this
forum has many people who know about what I'd like to ask: are there
any current or future platforms that use, or can be reasonably
expected to use, the COFF format for their binary files?

Background: Emacs has a bunch of implementation of unexec, one each
for every ABI used by platforms that Emacs can be built on.  (unexec
is a method of generating an executable binary file from an in-memory
image of a running program.)  There are, for example, unexelf.c for
ELF, unexw32.c for pe-coff, etc.  There's also unexcoff.c (renamed
yesterday from unexec.c), which was the original implementation
supporting a.out and COFF.  Nowadays, it is used only by the MSDOS
(a.k.a. DJGPP) build of Emacs.

The main issue is this: since only the MSDOS build uses unexcoff.c, I
was asked to clean it up of code that is #ifdef'ed away for the DOS
build.  My question is: can we reasonably assume that no future
platform where it makes sense to build Emacs will ever want to use
COFF?  If some modern low-end platforms (e.g., some mobile ones) use
or could use COFF, then perhaps some of the code currently unused by
the DOS build should be left in unexcoff.c, for the benefit of these
platforms.

TIA

Re: Platforms using COFF?

[Michael Snyder]

Eli Zaretskii wrote:
> I'm sorry for posting a slightly off-topic question, but I think this
> forum has many people who know about what I'd like to ask: are there
> any current or future platforms that use, or can be reasonably
> expected to use, the COFF format for their binary files?
> 
> Background: Emacs has a bunch of implementation of unexec, one each
> for every ABI used by platforms that Emacs can be built on.  (unexec
> is a method of generating an executable binary file from an in-memory
> image of a running program.)  There are, for example, unexelf.c for
> ELF, unexw32.c for pe-coff, etc.  There's also unexcoff.c (renamed
> yesterday from unexec.c), which was the original implementation
> supporting a.out and COFF.  Nowadays, it is used only by the MSDOS
> (a.k.a. DJGPP) build of Emacs.
> 
> The main issue is this: since only the MSDOS build uses unexcoff.c, I
> was asked to clean it up of code that is #ifdef'ed away for the DOS
> build.  My question is: can we reasonably assume that no future
> platform where it makes sense to build Emacs will ever want to use
> COFF?  If some modern low-end platforms (e.g., some mobile ones) use
> or could use COFF, then perhaps some of the code currently unused by
> the DOS build should be left in unexcoff.c, for the benefit of these
> platforms.

Not sure how meaningful, but...


grep -li coff config/*/*
config/djgpp/fnchange.lst
config/powerpc/aix.mh
config/rs6000/nm-rs6000.h

Re: Platforms using COFF?

[Eli Zaretskii]

> Date: Fri, 06 Aug 2010 11:20:59 -0700
> From: Michael Snyder <msnyder@vmware.com>
> CC: "gdb@sourceware.org" <gdb@sourceware.org>
> 
> grep -li coff config/*/*
> config/djgpp/fnchange.lst
> config/powerpc/aix.mh
> config/rs6000/nm-rs6000.h

Thanks.  Other than DJGPP, these are for AIX, I believe.  If that's
true, then AIX uses XCOFF, which seems to be already covered by
unexaix.c in Emacs.

Does anyone know which of the platforms hinted by bfd/coff-FOO.c are
still in widespread use?

Re: Platforms using COFF?

[Daniel Jacobowitz]

On Sat, Aug 07, 2010 at 12:16:42PM +0300, Eli Zaretskii wrote:
> > Date: Fri, 06 Aug 2010 11:20:59 -0700
> > From: Michael Snyder <msnyder@vmware.com>
> > CC: "gdb@sourceware.org" <gdb@sourceware.org>
> > 
> > grep -li coff config/*/*
> > config/djgpp/fnchange.lst
> > config/powerpc/aix.mh
> > config/rs6000/nm-rs6000.h
> 
> Thanks.  Other than DJGPP, these are for AIX, I believe.  If that's
> true, then AIX uses XCOFF, which seems to be already covered by
> unexaix.c in Emacs.
> 
> Does anyone know which of the platforms hinted by bfd/coff-FOO.c are
> still in widespread use?

Some of them are in use - but I'd be amazed if any of them ran emacs
:-)  You might want to check whether any of the NetBSD/OpenBSD
platforms are COFF, but I don't think so.

-- 
Daniel Jacobowitz
CodeSourcery

Re: Platforms using COFF?

[Mark Kettenis]

> Date: Sat, 7 Aug 2010 09:06:09 -0400
> From: Daniel Jacobowitz <dan@codesourcery.com>
> 
> On Sat, Aug 07, 2010 at 12:16:42PM +0300, Eli Zaretskii wrote:
> > > Date: Fri, 06 Aug 2010 11:20:59 -0700
> > > From: Michael Snyder <msnyder@vmware.com>
> > > CC: "gdb@sourceware.org" <gdb@sourceware.org>
> > > 
> > > grep -li coff config/*/*
> > > config/djgpp/fnchange.lst
> > > config/powerpc/aix.mh
> > > config/rs6000/nm-rs6000.h
> > 
> > Thanks.  Other than DJGPP, these are for AIX, I believe.  If that's
> > true, then AIX uses XCOFF, which seems to be already covered by
> > unexaix.c in Emacs.
> > 
> > Does anyone know which of the platforms hinted by bfd/coff-FOO.c are
> > still in widespread use?
> 
> Some of them are in use - but I'd be amazed if any of them ran emacs
> :-)  You might want to check whether any of the NetBSD/OpenBSD
> platforms are COFF, but I don't think so.

We (OpenBSD) have a few a.out platforms left (vax, m68k, m88k).  All
the others are ELF.  I believe NetBSD has been ELF-only for a while.

I believe we have a COFF bootloader for older PowerPC Macs, but I
doubt anybody will try to run emacs in that environment ;).

Re: Platforms using COFF?

[Eli Zaretskii]

> Date: Sat, 7 Aug 2010 15:23:20 +0200 (CEST)
> From: Mark Kettenis <mark.kettenis@xs4all.nl>
> CC: eliz@gnu.org, msnyder@vmware.com, gdb@sourceware.org
> 
> > Date: Sat, 7 Aug 2010 09:06:09 -0400
> > From: Daniel Jacobowitz <dan@codesourcery.com>
> > 
> > On Sat, Aug 07, 2010 at 12:16:42PM +0300, Eli Zaretskii wrote:
> > > > Date: Fri, 06 Aug 2010 11:20:59 -0700
> > > > From: Michael Snyder <msnyder@vmware.com>
> > > > CC: "gdb@sourceware.org" <gdb@sourceware.org>
> > > > 
> > > > grep -li coff config/*/*
> > > > config/djgpp/fnchange.lst
> > > > config/powerpc/aix.mh
> > > > config/rs6000/nm-rs6000.h
> > > 
> > > Thanks.  Other than DJGPP, these are for AIX, I believe.  If that's
> > > true, then AIX uses XCOFF, which seems to be already covered by
> > > unexaix.c in Emacs.
> > > 
> > > Does anyone know which of the platforms hinted by bfd/coff-FOO.c are
> > > still in widespread use?
> > 
> > Some of them are in use - but I'd be amazed if any of them ran emacs
> > :-)  You might want to check whether any of the NetBSD/OpenBSD
> > platforms are COFF, but I don't think so.
> 
> We (OpenBSD) have a few a.out platforms left (vax, m68k, m88k).  All
> the others are ELF.  I believe NetBSD has been ELF-only for a while.
> 
> I believe we have a COFF bootloader for older PowerPC Macs, but I
> doubt anybody will try to run emacs in that environment ;).

Thanks, guys.  I take it that I can safely leave only the DJGPP code
in unexcoff.c, right?

Re: Platforms using COFF?

[Mark Kettenis]

> Date: Sat, 07 Aug 2010 17:04:05 +0300
> From: Eli Zaretskii <eliz@gnu.org>
> 
> > Date: Sat, 7 Aug 2010 15:23:20 +0200 (CEST)
> > From: Mark Kettenis <mark.kettenis@xs4all.nl>
> > CC: eliz@gnu.org, msnyder@vmware.com, gdb@sourceware.org
> > 
> > > Date: Sat, 7 Aug 2010 09:06:09 -0400
> > > From: Daniel Jacobowitz <dan@codesourcery.com>
> > > 
> > > On Sat, Aug 07, 2010 at 12:16:42PM +0300, Eli Zaretskii wrote:
> > > > > Date: Fri, 06 Aug 2010 11:20:59 -0700
> > > > > From: Michael Snyder <msnyder@vmware.com>
> > > > > CC: "gdb@sourceware.org" <gdb@sourceware.org>
> > > > > 
> > > > > grep -li coff config/*/*
> > > > > config/djgpp/fnchange.lst
> > > > > config/powerpc/aix.mh
> > > > > config/rs6000/nm-rs6000.h
> > > > 
> > > > Thanks.  Other than DJGPP, these are for AIX, I believe.  If that's
> > > > true, then AIX uses XCOFF, which seems to be already covered by
> > > > unexaix.c in Emacs.
> > > > 
> > > > Does anyone know which of the platforms hinted by bfd/coff-FOO.c are
> > > > still in widespread use?
> > > 
> > > Some of them are in use - but I'd be amazed if any of them ran emacs
> > > :-)  You might want to check whether any of the NetBSD/OpenBSD
> > > platforms are COFF, but I don't think so.
> > 
> > We (OpenBSD) have a few a.out platforms left (vax, m68k, m88k).  All
> > the others are ELF.  I believe NetBSD has been ELF-only for a while.
> > 
> > I believe we have a COFF bootloader for older PowerPC Macs, but I
> > doubt anybody will try to run emacs in that environment ;).
> 
> Thanks, guys.  I take it that I can safely leave only the DJGPP code
> in unexcoff.c, right?

I'd say so.