OMF linkers

[rug...@gmail.com]

It's been brought up recently (in the other topic) that different linkers have different features, options, etc. We all know that OMF is (or was) the predominant object format for DOS-based systems. However, tools for this format have become neglected over the past dozen or so years (esp. since WinXP became ubiquitous). Hence, it's hard to find reliable OMF linkers for DOS outside of those that normally came with various compilers (old but presumably stable).

N.B. None of these is based upon any of my code. Also, I've not used these linkers very extensively at all (no millions of lines of code or anything). I just thought it was worth mentioning here that a few of them have become somewhat more "interesting" (at least in the past three or so years).

1). JWlink - http://www.japheth.de/JWlink.html

(EDIT: Huh, he just made a minor update three days ago. Though I doubt it changes much and is still "beta" ... I think the still-missing HX 2.17 release is waiting upon this to be improved / finalized / debugged).

This is basically Japheth's fork of OpenWatcom's WLINK, adding some features (e.g. 64-bit support, irrelevant for DOS) and improving MS LINK compatibility. It is built via OpenWatcom (and HX runtime libs, for DOS target), and thus is licensed the same as OW: Sybase v1 (OSI approved but Debian, Red Hat, FSF etc. hate it). Pre-compiled binaries exist for DOS, Linux, and Windows.

2). QLINK - http://www.sudleyplace.com/ , http://www.ibiblio.org/pub/micro/pc-stuff/freedos/files/util/system/sudley/

This is a DPMI-based DOS-hosted linker which also tries to mimic MS LINK. Fast, one-pass, handles USE32 bigger than 64 kb, and lots of error checking. However, its heavy DPMI requirement can be troublesome in some cases (DOSEMU?), but it claims to work on Win9x, and I know it can work in plain DOS (with related DPMIONE) or WinXP with included shims.

Last year it was thankfully released as GPLv3. However, the SVN link on the homepage is broken (though I've not bothered emailing the author for clarification). You can grab a previous (presumably still latest) snapshot of sources from iBiblio above. I don't know the tools needed to build this, presumably MASM or similar (I've not tried rebuilding).

3). Optlink - https://github.com/DigitalMars/optlink

This is the Win32-hosted linker included in Digital Mars (C/C++/D) compilers. Apparently it was first uploaded to GitHub about three years ago and still seems to get various patches. It claims to be a very fast (written in assembly!) 32-bit OMF linker. However, it seems that D 2.0 / DMD fans want MS COFF and/or 64-bit support these days (or such, I have no idea). All I know is that it exists, it allegedly builds okay now, and it may even (barely) work under Japheth's HX (dunno, simple tests may or may not work).

P.S. There are of course various other OMF linkers, some even with sources (VALX, Alink, DJlink), but either they aren't updated or are too buggy or similar. And there was some third-party who patches GNU ld to (partially) support some OMF informational stuff, but I don't think it was a full replacement. Keep in mind that OMF is usually considered legacy, esp. due to 16-bit origins, hence you'll be lucky to find a Win32 32-bit OMF linker, much less anything related to DOS (or OS/2 or Win16), still being developed. Nevertheless, for us DOS programmers, it's necessary to keep these tools in mind when delving into various projects (or just tinkering, like me).