This is a (very) simple loader for Linux that loads and executes a binary file in much the same way CP/M and DOS loaded .COM executables.
0x10000 bytes are allocated, starting at 0x0000. Binary files, up to 0xff00 bytes in length, are loaded starting at 0x100. Stack top is set to 0x10000 and loader jumps to instruction at 0x100.
What would be the program segment prefix (0x0000 - 0x0100) is left unused.
If you're confused, see this blog post for some details.
You can't run DOS .COM executables with this. Code is executed as a normal Linux process using the current architecture. No attempt is made to simulate x86 real mode or DOS services.
Disable the security feature that prevents us from mmaping the zero page (as root):
# sysctl vm.mmap_min_addr=0
Run make to build the loader, build a "Hello World" .COM binary and execute
it:
$ make
Hello, World!
To make kernel aware of the loader (as root):
# update-binfmts --install com /path/to/loader --extension com
Now you can run .COM binaries directly!
$ ./hello.com
Hello, world!
Linux COM loader was written by Tomaz Solc on a Monday evening. It is a silly thing not meant for serious use.
DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
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Copyright (C) 2004 Sam Hocevar <sam@hocevar.net>
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