This is the DJGPP Frequently-Asked Questions List.

Copyright © 1994, 1995, 1996, 1997, 1998, 2000 Eli Zaretskii.

This is the third edition of the FAQ list;
it is consistent with version 2.03 of DJGPP.

This FAQ list may be freely distributed with the DJGPP package or any part thereof, provided that this copyright notice is left intact on all copies.

Table of Contents

• DJGPP FAQ List
• 1 If You Are In a Hurry
• 2 What is DJGPP?
• 3 Hardware and Software Requirements
  • 3.1 The minimum system requirements for using DJGPP
  • 3.2 Does it really work under OS/2?
  • 3.3 Will DJGPP work on Windows/NT?
  • 3.4 Can it run under Linux?
  • 3.5 Can I run it on a 286?
  • 3.6 MS-Windows applications and DJGPP
  • 3.7 Machine you would like to buy...
  • 3.8 Machine most of us will actually buy ...
  • 3.9 How to configure your system for DJGPP
  • 3.10 How to get the most RAM for DJGPP programs?
• 4 Where and What to Download?
  • 4.1 Where can DJGPP be found?
  • 4.2 How do I download DJGPP?
  • 4.3 What if I don't know what FTP is?
  • 4.4 What Files to Download?
  • 4.5 How much disk space will I need?
  • 4.6 Can I get away with less megabytes?
  • 4.7 How to uninstall a DJGPP package.
• 5 The DJGPP Documentation
  • 5.1 Where are the documentation files?
  • 5.2 How to read the docs without Info?
  • 5.3 How to print the docs?
  • 5.4 Some docs are nowhere to be found...
  • 5.5 What are these foo.1 files?
  • 5.6 What if the docs don't say enough?
• 6 When the Compiler (or Make, or Info, or ...) Crashes...
  • 6.1 GCC or some other DJGPP programs hang
  • 6.2 GCC says "No DPMI"
  • 6.3 Buggy DPMI host or junk in DJGPP.ENV can crash v2.x programs
  • 6.4 GCC can crash during optimization
  • 6.5 Why does GCC say "cannot exec as"?
  • 6.6 What does "Internal compiler error" mean?
  • 6.7 What does "Unknown filetype" mean?
  • 6.8 Compiler hangs, but only when invoked from Make
  • 6.9 Info doesn't like some files
  • 6.10 Info Crashes During Startup
  • 6.11 Why does Bash crash?
  • 6.12 DJGPP programs crash on a ThinkPad
  • 6.13 Why does the Linker Access my CD Drive or the network?
  • 6.14 Other kinds of trouble
  • 6.15 I cannot keep up with the error messages
  • 6.16 How to search DJGPP archives
  • 6.17 How to ask DJGPP gurus for help
• 7 Compiler and Linker Performance
  • 7.1 Slow Compilation
  • 7.2 Slow Linking
• 8 Compile-time and Link-time Problems
  • 8.1 GCC doesn't find the source files
  • 8.2 GCC can't find headers or libraries
  • 8.3 GCC can't find C++ headers
  • 8.4 GCC barfs on C++-style comments in C programs
  • 8.5 How does GCC recognize the source language?
  • 8.6 Problems with Objective C
  • 8.7 Writing codes fragments which are specific to DJGPP
  • 8.8 Undefined references when linking programs
  • 8.9 How not to lose your head with all these libraries
  • 8.10 DJGPP uses a one-pass linker
  • 8.11 Some functions in C++ programs still not found
  • 8.12 Unresolved djgpp_first_ctor
  • 8.13 C++ programs yield large .exe file
  • 8.14 Why are DJGPP .exe files so large?
  • 8.15 Why don't we use DLLs to make programs smaller?
  • 8.16 Linker fails to produce the EXE program
  • 8.17 Building Allegro or GRX library fails
  • 8.18 C++ compiler says "NULL redefined"
  • 8.19 C++ exceptions support
  • 8.20 How to get GCC to generate assembly code
  • 8.21 What's wrong with sys/movedata.h?
  • 8.22 How do I create a library of object files?
  • 8.23 GCC Cannot find stubify.
• 9 Running Compiled Programs
  • 9.1 My program crashes only in v2.0!
  • 9.2 Programs that crash in malloc or free.
  • 9.3 The call stack traceback
  • 9.4 Reading and writing binary files
  • 9.5 Buffered screen I/O surprises
  • 9.6 What do DJGPP programs need to run?
  • 9.7 How many file handles can DJGPP use?
  • 9.8 DJGPP and Anti-Virus Software
• 10 Writing and Running Graphics Programs
  • 10.1 What GRX driver to use with your SVGA
  • 10.2 Accessing the video memory
  • 10.3 Graphics screen restoring under Windows
  • 10.4 OpenGL and related packages for DJGPP
• 11 Floating Point Issues and FP Emulation
  • 11.1 Floating-point code without 80387
  • 11.2 Floating point inaccuracies when using emulator
  • 11.3 Problems with emulation on Windows
• 12 Debugging DJGPP Programs
  • 12.1 How to run a DJGPP program under debugger
  • 12.2 How to begin debugging using the crash dump info
  • 12.3 How to debug a graphics program
  • 12.4 GDB finds only .cc source
  • 12.5 Can GDB print class members?
  • 12.6 GDB cannot list source that was #include'd
  • 12.7 GDB cannot display or set static uninitialized variables
  • 12.8 Debugging bool data type
  • 12.9 Debugging the complex data type
  • 12.10 Debuggers choke on some programs ...
• 13 Profiling DJGPP Programs
  • 13.1 How to profile a DJGPP program
  • 13.2 Programs compiled with -pg crash when run
  • 13.3 Gprof produces garbled profile
  • 13.4 Why is __dpmi_int so heavily used?
  • 13.5 gprof doesn't produce output
• 14 Run-time Performance of DJGPP Programs
  • 14.1 How efficient is DJGPP-generated code?
  • 14.2 Comparing newer versions with old ones
  • 14.3 DJGPP programs on a Pentium
  • 14.4 I/O speed in DJGPP programs
  • 14.5 My ported program runs much slower!
• 15 Run-Time Memory Issues
  • 15.1 How much virtual memory do you have?
  • 15.2 It seems malloc/free don't affect virtual memory...
  • 15.3 Failure to get more memory than is physically installed
  • 15.4 Memory allocation fails before all memory is used
  • 15.5 Memory allocation fails under Windows
  • 15.6 Memory allocation peculiarities under Windows 9X
  • 15.7 Memory allocation fails under EMM386 or HIMEM
  • 15.8 How much memory do parent DJGPP programs leave for their child?
  • 15.9 How much stack can I have in DJGPP programs?
  • 15.10 Memory-related problems in Windows 98
• 16 Command-line Arguments Handling in DJGPP
  • 16.1 Filename wildcards expansion under DJGPP
  • 16.2 How to disable filename wildcards expansion
  • 16.3 How to pass command-line arguments with quotes or @
  • 16.4 How to pass command lines longer than 126 characters
  • 16.5 What is the maximum length of command line under DJGPP
  • 16.6 Why Make passes only 126 characters to programs?
• 17 Converting DOS Programs/Libraries to DJGPP
  • 17.1 GCC/Gas won't accept valid assembly code ...
  • 17.2 Converting between Intel ASM syntax and AT&T syntax
  • 17.3 Converted code GP Faults!
  • 17.4 Problems with combining assembly and C/C++ modules
  • 17.5 I want to use a .obj or .lib code with DJGPP
  • 17.6 I must use my 16-bit code with DJGPP!!
  • 17.7 What should I do with those "near" and "far" declarations?
  • 17.8 How to convert _AX pseudo-registers?
• 18 Low-level DOS/BIOS and Hardware-oriented Programming
  • 18.1 Got "Unsupported INT 0xNN" calling int86
  • 18.2 How to use buffers with DOS/BIOS services
  • 18.3 How to call real-mode functions
  • 18.4 How to move data between your program and conventional memory
  • 18.5 How to move structs returned by real-mode services?
  • 18.6 Fast access to absolute addresses
  • 18.7 Accessing absolute address above 1MB
  • 18.8 How to make DOS/BIOS call your function
  • 18.9 How to hook hardware interrupts
  • 18.10 Should I use _go32_XXX or __dpmi_YYY functions?
  • 18.11 Hardware interrupt hooking has its subtleties
  • 18.12 Inline Assembly code with GCC
  • 18.13 Using DMA with DJGPP
• 19 Legal Aspects
  • 19.1 Legal (un)restrictions on DJGPP applications
  • 19.2 Legal restrictions of DJGPP utilities and libraries
• 20 Getting Help
  • 20.1 Don't post DJGPP-specific problems to GNU News groups
  • 20.2 How to post to the DJGPP forum
  • 20.3 How to become a subscriber to the mailing list
  • 20.4 How to unsubscribe from the mailing list
  • 20.5 Is it okay to post messages in languages other than English?
• 21 Version 2 vs v1.x
  • 21.1 New features in DJGPP v2
  • 21.2 DJGPP environment in v2.x
  • 21.3 Why are new DJGPP versions released so slowly?
  • 21.4 Where to find the best C library for DJGPP
• 22 Miscellany
  • 22.1 Problems with using RHIDE.
  • 22.2 Unzipping complains about duplicate/invalid files.
  • 22.3 How to change a DJGPP package?
  • 22.4 Where to find DJGPP packages?
  • 22.5 How to create symbolic links to programs
  • 22.6 Where to find the DPMI specification?
  • 22.7 The DJGPP Web site.
  • 22.8 Where to upload your contributions to DJGPP
  • 22.9 DJGPP as cross-compiler
  • 22.10 GCC says "garbage at end of number"
  • 22.11 What should sizeof (struct xyzzy) return?
  • 22.12 C++ doesn't pack structs!
  • 22.13 How to avoid "Abort, Retry, Fail" messages
  • 22.14 What is that go32-v2.exe program?
  • 22.15 What is DXE?
  • 22.16 Long Filenames Don't Work!
  • 22.17 Make says "missing separator"
  • 22.18 Make says "foo has modification time in the future"
  • 22.19 How to Set Up a Dual DOS/Windows Installation
  • 22.20 What is in that zoneinfo directory?
  • 22.21 The dark secrets of the /dev/ directory...
  • 22.22 How about switching to ELF as DJGPP's object file format?
  • 22.23 How to produce random numbers?
  • 22.24 What are all these buzzwords I see?
  • 22.25 What should the main function return in a C/C++ program?
  • 22.26 Rebooting the PC from a DJGPP program
  • 22.27 Delaying execution for short periods of time
  • 22.28 CGI programs and DJGPP
  • 22.29 Why Do I Get EOF From stdin?
  • 22.30 Generating the FAQ in your favorite format
• 23 About this FAQ
• 24 Topic Index
• 25 Program Index