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A "hello world" program in machine code on DOS
blog · git · desktop · images · contact 2024-09-29 I watched this nice (German) talk: https://media.ccc.de/v/ds24-394-linux-hello-world-nur-mit-einem-hex-editor It walks you through the process of writing a "hello world" program for 64-bit Linux in a hex editor. There's no assembler involved, you write the machine code directly.
This slightly strange mechanism means that several pairs of segment selectors and offsets actually map to the same linear addresses. If we wouldn't issue an exit request, the CPU would just continue to execute arbitrary memory content, i.e. garbage, i.e. the program would very likely "crash". I'd recommend downloading the volumes as individual files ("Ten-Volume Set of Intel 64 and IA-32 Architectures Software Developer's Manuals"), because the full documentation is over 5000 pages long and hard(er) to navigate.
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