The Sortix Operating System =========================== Sortix is a hobby operating system. It was originally created as a tool to learn more about kernel and operating system design and implementation. Today it is gradually transforming into a real operating system. The standard library and kernel is rich enough that some third party software can and has been ported to Sortix. While the system remains limited, there have been added support for bitmap graphics and proper filesystem support is being worked on. Unfortunately there is no support for networking yet. The current release ships with various test programs, utility programs and a few games and has support for rendering the console in graphics mode. The system aims to be an Unix-clone and is heavily based on POSIX. However, I've drawn much inspiration from systems such as Plan 9, GNU/Hurd and MINIX. While the system doesn't strive to be a microkernel (and today isn't), the plan is to have user-space filesystems, per-process namespaces, subusers, and generally give regular users more power that traditional Unix systems. If you are interested, you can read about my design decisions at http://maxsi.org/blog/. System Requirements ------------------- Sortix has very low system requirements. It also works well under virtual machines such as VirtualBox and Qemu. * A 32-bit x86 (with SSE) or 64-bit x86_64 CPU. * A dozen megabytes of RAM. * A harddisk or cdrom drive or support for booting from USB. * A multiboot compliant bootloader if booting from harddisk. * A Parallel ATA harddisk, if you wish to access it from Sortix. SATA is not supported yet. Features -------- The current development version of Sortix offers a traditional multi-process protected environment with round-robin scheduling. A quick and dirty shell is able to execute programs in foreground or background mode, handle IO redirection and piping the standard output of a process into the standard input of another. A real shell will be added as the system matures and I get around to finish the work-in-progress shell. The official distribution contains a number of small utilities one would expect on a unix system, such as cp, cat, ls, and so on. There are a lot of common utilities missing as I haven't coded them yet. The purpose of the current userspace is simply to test the system so don't expect too much. Unfortunately, for technical reasons, I don't distribute ported third party software along with Sortix. This is largely because the build system sucks but also that statically linked libraries are big and the initrd is already big enough as it is. However, I have successfully ported binutils, gcc, gzip, zlib, freetype, GNU hello, and more. Once proper filesystem support is merged, I can distribute third party software separately and it can be mounted during boot. A number of small games is present and uses the VGA textmode to render ASCII graphics. Notably you can play two-player Pong, or single-player Snake, or the nice and Turing-complete Conway's Game of Life. There is also a small remake of the asteroids game which uses 32-bit bitmap graphics. These are probably the main attraction of the system for non-technical people. The Sortix kernel has very basic filesystem support. The root filesystem / is simply a single-directory RAM filesystem. The init ramdisk is mounted read-only on /bin and various devices are accessible through the /dev filesystem. Work is underway to create an ext2 filesystem server, but it won't be of much use until the kernel virtual filesystem is completed in the 0.8dev development cycle. There currently is no concept of users in the system (only the root user exists). I decided to delay making a multi-user system until the base system is in place. Note that there is only a single terminal - even though the system is a multi-process system, there is only a single graphics framebuffer and there is no framework for sharing it. Improvements in Sortix 0.7 -------------------------- The 0.7 release improves greatly upon Sortix 0.6. * Multithreaded and fully preemptive kernel. * Support for Streaming SIMD Extensions (SSE) and floating point numbers. * Support for bitmap graphics through new /dev/video/ framework. * Environmental variables. * Rewritten and powerful initrd format. * Init restarts the shell if it crashes. * BGA graphics driver. * Console rendering in graphics mode. * Asteroids remake. * Improved signal handling. * VEOF support in terminal driver and shell. * Various shell improvements. * Implement scanf function family. * Support for using PAT and MTRR to speed up video memory access. * Countless improvements to the kernel and the standard library. In addition, a BIOS call driver was created during the 0.7 cycle as well as a VBE graphics driver. However, the BIOS driver only worked on 32-bit CPUs and hence wasn't merged in time. As the VBE driver depended on it, it was cut too. Known bugs ---------- There is currently a lot of bugs and small quirks in Sortix. They are caused by the system being young and incomplete. They will gradually be fixed as the base system improves. They are tolerated in the releases because they are not critical and improvement situation from the last release. The shell only looks at whitespace when parsing input lines. This means that operators such as & ; and | must be surrounded by whitespace on both sides. While quotes aren't implemented, you can work around this by using backslahes to escape all characters except newlines. The shell does not accept very long lines yet. Some programs change the format of the terminal standard input delivered to them. For instance, the pong game needs to capture every keyboard event. However running such programs at the same time as programs that need proper line- buffered input (such as the shell) causes conflicts and neither program gets what it needs causing programs to exit or crash. Note that if the shell fails to read in its expected format, it exits with an error code. This issue is caused by the design of the terminal system and can't be fixed until it is rewritten. The editor can only run in 80x25 terminal resolutions. This is because it is very hacky and was written before malloc worked. This will be fixed when the editor is rewritten. The filesystem is currently hacked together in the kernel. When things go wrong you may experience the utilities returning the wrong error codes. This is harmless but confusing. All the current kernel filesystem code will be replaced a user-space filesystem framework and will be present in the next release. The system can partially deadlock if a process exits and zombie children are not collected yet. Improvements scheduled for Sortix 0.8 ------------------------------------- * New build system based on cross compilation and package management. * Merge BIOS and VBE drivers. * Kernel virtual filesystem. * User-space filesystem framework. * User-space ext2 filesystem driver. * Refactor and extend the standard library. * Mount-points. * Improved terminal framework. * New and improved shell. * Copy-on-write in fork(2) and mmap(2). * Pointer-safe system calls. * And various misc. improvements. Technical details ---------------- The system is mostly coded in C++, but also contains a few files in C. However, the user-land experiences a normal C programming interface as per POSIX. Executable files natively uses the ELF format used on GNU/Linux and other systems. There is no shared library support yet, but it'll be possible when I get around to implement copy-on-write memory, mmap(2) and swapping to disk. Building -------- To build the Sortix source code you need to install a few dependencies. First of all you need the GNU Compiler Collection (C and C++), GNU Make, and GNU Binutils. You then need to build and install the included macro preprocessor (mxmpp) somewhere in your PATH such as /usr/bin. You need a GNU/Linux build system to build Sortix, although, it wouldn't be difficult to port the build system to other platforms. You can then build the Sortix kernel and user-space utilities by running make in the Sortix root source directory. By default it will build to your CPU architecture (64-bit on 64-bit systems, 32-bit otherwise). Use CPU=x86 or CPU=x64 as arguments to make to control which target is built. To build a bootable ISO you need GNU GRUB 2, as that is used by "make iso" to generate the iso. In turn, GNU GRUB relies on xorriso to create the iso file. You can burn the ISO to a cdrom or dvd, or even dd(1) it onto a USB memory stick and boot from if it your BIOS supports it. You can also provide it to a virtual machine. Alternatively you can install the kernel binary and initrd in your /boot directory and configure GRUB to boot Sortix. Links ----- You can visit the official website at http://www.maxsi.org/software/sortix/ for more information and news. You can also download the newest release and cutting edge nightly builds from https://cs.au.dk/~sortie/sortix/release/. You can retrieve the current git master from our gitorious project page from https://gitorious.org/sortix/. You can read my blog where I discuss various design decisions in Sortix at http://maxsi.org/blog/. License ------- Copyright(C) Jonas 'Sortie' Termansen and contributors 2011, 2012. Sortix is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the gpl.html and lgpl.html files for more information. See the individual files for copyright terms. If a file does not contain a license header, you can assume it is released under the GNU General Public Licenser, either version 3 or (at your option) any later version. This includes Sortix-related experimental branches and repositories found on Gitorious: these things are so experimental that I didn't add copyright statements. Unless the license header in the source code states otherwise, the Sortix kernel, the filesystem servers, the initrd tools, the utilities, the games, and the benchmark programs are licensed under the GNU General Public License, either version 3 or (at your option) any later version. Unless the license header in the source code states otherwise, the libc library s licensed under the GNU Lesser General Public License, either version 3 or (at your option) any later version.