Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!elroy.jpl.nasa.gov!decwrl!infopiz!lupine!rfg From: rfg@NCD.COM (Ron Guilmette) Newsgroups: comp.os.mach Subject: Re: Mach-O and COFF Message-ID: <5416@lupine.NCD.COM> Date: 6 May 91 15:35:04 GMT References: <1991Apr30.054735.7606@mnemosyne.cs.du.edu> <7552@auspex.auspex.com> Distribution: na Organization: Network Computing Devices, Inc., Mt. View, CA Lines: 43 In article <7552@auspex.auspex.com> guy@auspex.auspex.com (Guy Harris) writes: +>and you can also store core dumps in Mach-O! + +COFF's replacement in S5R4, ELF, also allows this. + +>Mach-O is more universal, it allows you to assign start values to +>registers (does this work in COFF as well? - I dunno.) + +Neither COFF nor ELF, as I remember, have this, although one way to +assign start values to registers is to stick code to do so at the start +address - is the ability to have "exec*()" or its moral equivalent load +arbitrary values to registers useful enough that this feature is worth +having? + +>So if COFF isn't that compatible anyway, why not start from scratch +>and have a clean start? + +AT&T appears to agree, hence ELF.... As Guy points out, AT&T started fresh on object-file/core-dump formats in System V Release 4. They also started fresh when it came to the format used to put symbolic debugging information into their "ELF" object files. Unlike the bad old COFF days, AT&T now uses two separate names for their object file format and for their symbolic debugging information format. The former is called "ELF" while the latter is called "DWARF". Like ELF, DWARF is a significant improvement over what went before. I've done the work to add DWARF generation to the GNU C compiler, and I'm also now working on adding DWARF support to the GNU debugger (GDB). Thus, I've had ample opportunities to see DWARF close up, and I'm mostly pleased with what I've seen. Now I know that some users of MACH will probably be using the debug info format that OSF has done (i.e. "ROSE") but I wonder what other non-OSF users of MACH are using (or are planning to use) when it comes to a debugging information format? Are non-OSF MACH users using BSD stabs? If so, why? -- // Ron ("Loose Cannon") Guilmette // Internet: rfg@ncd.com uucp: ...uunet!lupine!rfg // New motto: If it ain't broke, try using a bigger hammer.