66 lines
2.2 KiB
Groff
66 lines
2.2 KiB
Groff
.TH INTRO 1
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.SH NAME
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intro - introduction to ZenithOS userspace
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.SH DESCRIPTION
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ZenithOS is a hobbyist 64-bit operating system written in C++20.
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Userspace programs run in Ring 3, are loaded as static ELF64
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binaries, and communicate with the kernel through the x86-64
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SYSCALL/SYSRET mechanism.
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Programs are compiled with a freestanding cross-compiler and
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linked at virtual address 0x400000. There is no standard C
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library for C++ programs -- all system interaction goes through
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the zenith:: syscall wrappers.
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.SH GETTING STARTED
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To write a new program, create a directory under programs/src/
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with a main.cpp file. The entry point is:
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extern "C" void _start() { ... }
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There is no argc/argv. Use zenith::getargs() to retrieve any
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arguments passed by the parent process. Include <zenith/syscall.h>
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for the full typed syscall API.
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Build with:
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cd programs && make
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The resulting ELF binary appears in programs/bin/os/.
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.SH RAMDISK LAYOUT
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The boot ramdisk is mounted as drive 0 with the following
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directory structure:
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0:/os/ System binaries (shell, init, man, etc.)
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0:/games/ Games (doom)
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0:/man/ Manual pages
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0:/www/ Web server content
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0:/home/ User home directory
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.SH SHELL
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The interactive shell is the primary way to interact with
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ZenithOS. Commands are resolved by searching the PATH
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directories (0:/os/, 0:/games/) for matching .elf binaries.
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Type 'help' at the shell prompt for a list of commands.
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Use 'man shell' for detailed shell documentation.
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.SH MAN PAGES
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The following man pages are available:
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intro(1) This page
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shell(1) Shell commands reference
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init(1) Init system
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dhcp(1) DHCP client
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man(1) The man command itself
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legal(7) Copyright and legal information
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syscalls(2) Overview of all syscalls
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spawn(2) Process spawning
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file(2) File I/O syscalls
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framebuffer(2) Framebuffer access
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malloc(3) Memory allocation
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.SH SEE ALSO
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shell(1), syscalls(2), malloc(3)
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