yetmorecode / ghidra-lx-loader

Ultimate Ghidra loader for the LX/LE executable file format (OS/2, DOS4GW, VxD)

Ultimate Ghidra Loader for the LX/LE executable file format

Download a zip matching your Ghidra version from releases and install it from File > Install extensions...

Features

• Supports LE/LX files in various formats:
  • OS/2 LX-Style
  • MSDOS DOS/16 LE-Style
  • MSDOS DOS/4 LE-Style
  • DOS32A sb.exe unbound LE/LX-Style
  • Windows Virtual Device Driver (VxD)
• Full page-map and fixup (relocation) support
• Completely typed executable headers (and other image data) with comments

Optionally, various options can be specified individually for each file:

• Manually override the object base addresses and segment selectors (good for syncing with a debugger / DOSBox)
• Map various image data to an overlay:
  • Map MZ Header
  • Map LX Header
  • Map LX Loader Section
  • Map LX Fixup Section (fully typed!)
  • Map LX Data Section (i.e. the unmodified page data)
• Create labels for each fixup in memory
• Create labels for each page beginning in memory
• Log fixup statistics / Log individual fixup types

Tested with

• F1 Manager Professional (F1.exe - DOS/4GW LE): https://www.mobygames.com/game/dos/f1-manager-professional
• The Elder Scrolls Redguard (RGFX.exe - DOS/4GW LE): https://en.wikipedia.org/wiki/The_Elder_Scrolls_Adventures:_Redguard
• X-Com: Apocalypse (UFO2P.EXE - DOS/16 LE and unbound LE-style)
• Various files compiled with Open Watcom (DOS32A LE)
• Random VxD files

Extra

Manually overriding base addresses and segment selectors

The loader can be instructed to manually override the base addresses and selectors of the executable's objects. I use this to feed Ghidra the same memory layout and segment selectors as I find in the dosbox debugger. In return I can use the same addresses found in Ghidra to set breakpoints in the debugger etc.

To override the base addresses, just enter a comma-seperated list of hex values into the field:

The loader will adjust the locations (and fixups!) accordingly:

Resources

• https://ghidra-sre.org/
• https://moddingwiki.shikadi.net/wiki/Linear_Executable_(LX/LE)_Format
• https://github.com/yetmorecode/dos32a/blob/master/src/dos32a/loader.asm
• https://github.com/open-watcom/open-watcom-v2/blob/master/bld/watcom/h/exeflat.h

Feedback

If you got any feedback, please don't hesitate to open a ticket. Even if you are just using the loader without any issues I'd be happy to hear about :)