In this short article I want to show the basics of how to generate an executable for the DragonFly BSD operating system from a Linux system. This process is called cross compiling. The reason why I investigated into this topic was that I wanted to cross-compile the Rust compiler.
All you need is clang installed and a DragonFly BSD installer ISO image which you can obtain from it’s homepage. The application we want to cross-compile is the one listed below:
#include <stdio.h>
int main(int argc, char **argv) {
printf("Hello World\n");
return 0;
}
The first step is to mount the ISO image into the local directory ./iso because we need the header files for compilation as well as the files crt{1,i,begin}.o and libgcc.a for linking.
mkdir iso
sudo mount -o loop,ro DragonFly-x86_64-LATEST-ISO.iso ./iso
After that, we are ready to compile our simple Hello World example application. To compile we need to specify the corresponding include and link paths and tell the compiler the target we want to create code for, in our case this is x86_64-pc-dragonfly-elf.
clang -I./iso/usr/include \
-L./iso/usr/lib -L./iso/usr/lib/gcc47 \
-B./iso/usr/lib -B./iso/usr/lib/gcc47 \
-target x86_64-pc-dragonfly-elf \
-o hw hw.c
Running file hw should now display something like this:
hw: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked
(uses shared libs), for DragonFly 3.0.702, not stripped
Voilà, there it is, our binary for DragonFly BSD.