197 lines
4.8 KiB
Markdown
197 lines
4.8 KiB
Markdown
# NT-Lite -- an x86-64 kernel
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“Not only is UNIX dead, it’s starting to smell really bad.” - Rob Pike
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“UNIX has three operations: read, write, and lie through ioctl.”
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## what is it?
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NT-Lite is a 64-bit operating system kernel written from scratch.
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It boots into a shell, loads drivers, launches programs, survives application crashes, runs Doom, plays video, talks TCP/IP, and occasionally reminds you that it is still a hobby kernel.
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The codebase is small enough to understand, but no longer small enough to pretend it is just a weekend project.
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## features
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- UEFI bootloader
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- real SMP
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- physical and virtual memory managers
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- kernel pool and user heap
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- single address-space design with user/supervisor page permissions
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- HAL split from the kernel
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- preemptive priority scheduler
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- processes and threads
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- per-process handles with rights checks
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- process exit state, reaping, and restartable init services
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- events, semaphores, mutexes, queues, named queues, and alertable waits
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- IRQL, DPCs, kernel APCs, and user APCs
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- native user-mode exception dispatch
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- Win32 vectored exception handlers
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- minimal runtime-registered SEH substrate
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- async file I/O with events, IOSBs, APC callbacks, and cancellation
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- VFS with IRPs
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- page cache with dirty writeback and invalidation
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- AHCI driver, interrupt-driven
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- IDE driver, PIO/DMA
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- FAT32 filesystem driver with VFAT long names
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- USB bus, xHCI, mass storage, and HID
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- VMware SVGA display driver
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- drive-number paths such as `0:/apps/shell.exe`
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- PE import resolution and dynamic `.sys` driver loading
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- modular networking through lwIP
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- RTL8139 and RTL816x network drivers
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- native BSD-ish socket syscalls
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- DNS resolver syscall
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- length-tracked string-view syscall ABI
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- request-struct based syscalls for larger calls
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- native `NTLSTATUS_*` status codes
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- INI-based configuration
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- partial Win32 personality
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- partial (microsoft-level) POSIX personality
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- Doom
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- video playback
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- fully GDPR-compliant
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- everything but the kitchen sink
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## paths
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```text
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"apps/shell.exe" -> current working directory
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"0:/apps/shell.exe" -> volume 0, native path; works everywhere
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"2:/data/config.ini" -> volume 2, native path
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"C:\apps\doom.exe" -> volume 0 through win32.dll; C: maps to 0:, D: maps to 1:, etc.
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"/apps/video.exe" -> volume 0 through posix.dll
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"/1/apps/video.exe" -> volume 1 through posix.dll
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```
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Volumes `0`-`7` are available. A volume only works if a filesystem is registered on it.
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The Win32 personality translates drive letters to volume numbers. The POSIX personality maps volumes into a tree.
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## how to build
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- open the VS x64 build tools as administrator
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- change into this directory
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- run `build.bat`
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- use one of:
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- `run.bat` — IDE
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- `rund.bat` — IDE, debug
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- `runa.bat` — AHCI
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- `runad.bat` — AHCI, debug
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## how it looks when built
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```text
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efi/boot/
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bootx64.efi
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boot.ini
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drivers/
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drivers.ini
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ahci.sys
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ata.sys
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fat32.sys
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lwip.sys
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pci.sys
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ps2.sys
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rtl816x.sys
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rtl8139.sys
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usb.sys
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vmwaresvga.sys
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system/
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colonel.exe
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hal.dll
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init.exe
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syscall.dll
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win32.dll
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posix.dll
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apps/
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shell_native.exe
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shell_win32.exe
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shell_posix.exe
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async_apc.exe
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async_cancel.exe
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doom.exe
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video.exe
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httpget.exe
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tcpserve.exe
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udp.exe
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resolve.exe
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ping.exe
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```
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## screenshots
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## faq
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Q: Is it secure?
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A: Don't connect to the internet with it.
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Q: Who is this for?
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A: Me.
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Q: What's next?
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A: todo
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Q: Does it run Doom?
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A: `doom.exe`
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Q: Does USB work?
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A: It did for everything I threw at it.
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Q: If I write a program now, will it run in the future?
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A: WE DO, in fact, BREAK USERSPACE.
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Q: Can you read and write files?
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A: As far as I'm aware.
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Q: Does it have async I/O?
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A: The best you'll get.
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Q: Does the networking actually work?
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A: It didn't crash yet.
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Q: Does it really have SMP?
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A: Watch out. It bites.
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Q: Is the Win32 layer real?
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A: Depends how you frame it. Real apps won't run but specifically prepared ones will.
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Q: Are processes isolated?
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A: No. But IPC is free. Is this how a serious modern OS should isolate processes? No.
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Are we a serious OS? No. Is it very convenient? Absolutely.
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Q: How often does it crash?
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A: It doesn't if you don't touch it.
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Q: Can it recover from a crash?
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A: Works on my machine.
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Q: Is this finished?
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A: It will be once I get a job.
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Q: Will it corrupt my data?
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A: It shouldn't.
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Q: Why is the path syntax so weird?
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A: It makes sense to me.
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Q: Why both Win32 and POSIX?
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A: NT could do it, why can't I?
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Q: Why are the logs so verbose?
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A: Try debugging an interrupt path with vibes.
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Q: What should I read first?
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A: This document.
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Q: How do I contribute?
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A: `maksw@maksw.pl`
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Q: Can I use this in production?
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A: Don't.
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#### Project dedicated to the honorable, esteemed Professor Leszek Wójcik through whom I came to hate Unix.
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