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When cloning an AnonymousVMObject, committed COW pages are shared between the parent and child object. Whicever object COW's first will take the shared committed page, and if the other object ends up doing a COW as well, it will notice that the page is no longer shared by two objects and simple remap it as read/write. When a child is COW'ed again, while still having shared committed pages with its own parent, the grandchild object will now join in the sharing pool with its parent and grandparent. This means that the first 2 of 3 objects that COW will draw from the shared committed pages, and 3rd will remap read/write. Previously, we would "fork" the shared committed pages when cloning, which could lead to a situation where the grandparent held on to 1 of the 3 needed shared committed pages. If both the child and grandchild COW'ed, they wouldn't have enough pages, and since the grandparent maintained an extra +1 ref count on the page, it wasn't possible to to remap read/write.
SerenityOS
Graphical Unix-like operating system for x86 computers.
About
SerenityOS is a love letter to '90s user interfaces with a custom Unix-like core. It flatters with sincerity by stealing beautiful ideas from various other systems.
Roughly speaking, the goal is a marriage between the aesthetic of late-1990s productivity software and the power-user accessibility of late-2000s *nix. This is a system by us, for us, based on the things we like.
I (Andreas) regularly post raw hacking sessions and demos on my YouTube channel.
Sometimes I write about the system on my github.io blog.
I'm also on Patreon and GitHub Sponsors if you would like to show some support that way.
Screenshot
Kernel features
- x86 (32-bit) kernel with pre-emptive multi-threading
- Hardware protections (SMEP, SMAP, UMIP, NX, WP, TSD, ...)
- IPv4 stack with ARP, TCP, UDP and ICMP protocols
- ext2 filesystem
- POSIX signals
- Purgeable memory
- /proc filesystem
- Pseudoterminals (with /dev/pts filesystem)
- Filesystem notifications
- CPU and memory profiling
- SoundBlaster 16 driver
- VMWare/QEMU mouse integration
System services
- Launch/session daemon (SystemServer)
- Compositing window server (WindowServer)
- Text console manager (TTYServer)
- DNS client (LookupServer)
- Network protocols server (RequestServer and WebSocket)
- Software-mixing sound daemon (AudioServer)
- Desktop notifications (NotificationServer)
- HTTP server (WebServer)
- Telnet server (TelnetServer)
- DHCP client (DHCPClient)
Libraries
- C++ templates and containers (AK)
- Event loop and utilities (LibCore)
- 2D graphics library (LibGfx)
- OpenGL 1.x compatible library (LibGL)
- GUI toolkit (LibGUI)
- Cross-process communication library (LibIPC)
- HTML/CSS engine (LibWeb)
- JavaScript engine (LibJS)
- Markdown (LibMarkdown)
- Audio (LibAudio)
- PCI database (LibPCIDB)
- Terminal emulation (LibVT)
- Out-of-process network protocol I/O (LibProtocol)
- Mathematical functions (LibM)
- ELF file handling (LibELF)
- POSIX threading (LibPthread)
- Higher-level threading (LibThreading)
- Transport Layer Security (LibTLS)
- HTTP and HTTPS (LibHTTP)
- IMAP (LibIMAP)
Userland features
- Unix-like libc and userland
- Shell with pipes and I/O redirection
- On-line help system (both terminal and GUI variants)
- Web browser (Browser)
- C++ IDE (HackStudio)
- IRC client
- Desktop synthesizer (Piano)
- E-mail client (Mail)
- Various desktop apps & games
- Color themes
How do I read the documentation?
Man pages are available online at man.serenityos.org. These pages are generated from the Markdown source files in Base/usr/share/man and updated automatically.
When running SerenityOS you can use man for the terminal interface, or help for the GUI.
How do I build and run this?
See the SerenityOS build instructions
Before opening an issue
Please see the issue policy.
FAQ: Frequently Asked Questions
Get in touch
Join our Discord server: SerenityOS Discord
Author
- Andreas Kling - awesomekling
Contributors
- Robin Burchell - rburchell
- Conrad Pankoff - deoxxa
- Sergey Bugaev - bugaevc
- Liav A - supercomputer7
- Linus Groh - linusg
- Ali Mohammad Pur - alimpfard
- Shannon Booth - shannonbooth
- Hüseyin ASLITÜRK - asliturk
- Matthew Olsson - mattco98
- Nico Weber - nico
- Brian Gianforcaro - bgianfo
- Ben Wiederhake - BenWiederhake
- Tom - tomuta
- Paul Scharnofske - asynts
- Itamar Shenhar - itamar8910
- Luke Wilde - Lubrsi
- Brendan Coles - bcoles
- Andrew Kaster - ADKaster
- thankyouverycool - thankyouverycool
- Idan Horowitz - IdanHo
- Gunnar Beutner - gunnarbeutner
- Tim Flynn - trflynn89
- Jean-Baptiste Boric - boricj
- Stephan Unverwerth - sunverwerth
- Max Wipfli - MaxWipfli
- Daniel Bertalan - BertalanD
(And many more!) The people listed above have landed more than 100 commits in the project. :^)
License
SerenityOS is licensed under a 2-clause BSD license.