TRIX

TRIX is a remote procedure call kernel, developed by the Massachusetts Institute of Technology and whose authors decided that it should be freely distributed; Trix was fully compatible with UNIX Version 7.

Design and implementation

TRIX is based on the initialization of each CPU in the system with the same program, passing to each instance the numerical ID of the CPU on which it is executed. With this, TRIX got the first CPU configured globally, setting the corresponding FLAG to each instance when it is initialized. After this, each kernel instance could access global data, although private data could also be accessed as long as you had the necessary permission.

The filesystem could be accessed by an application from user space.

The kernel supported unnamed threads running on domains, where each domain is an equivalent of a UNIX process (but without any stack pointers). A thread could change the domains, the reference name and the implementation itself of the processors associated with the system. The system scheduler would migrate threads between CPUs, in order to keep the processors busy for as long as possible.

The "garbage collector" or the system garbage collector made it a priority to remove garbage, identify other threads periodically, and free unused domains. The shared memory model, used to coordinate work between CPUs, caused high latencies on the memory bus, creating an inefficient system. The TRIX system began by implementing a system for passing messages between non-blocking CPUs, something the designers themselves were aware of.

Although the TRIX operating system was initially implemented on a NuMachine, its main advantage was that this operating system was very portable. It was designed in C language and assembler.

Attempted use by the GNU Project

Richard Stallman mentions in the 1985 GNU MANIFESTO that there is an initial kernel for the GNU operating system, although many more features are needed to emulate a UNIX system. (This was a reference to the TRIX kernel, where its authors decided to distribute it as free software.

During a speech in October 1986, Stallman explained that the TRIX kernel was executable, but had incompatibility with UNIX systems in certain parts of the project (although more still needed to be developed). Currently TRIX systems use a file system that shares the same structure as UNIX systems on disk. This made debugging much easier, since they could configure the files with UNIX and run TRIX afterwards. In December 1986, the developers used the TRIX kernel as their first attempt to generate the kernel for GNU. Later, they found that TRIX was unfeasible as a starting point for GNU.

• It only ran on "a dark and face black box 68000", so then it required this system of portability to other architectures.
• It was decided that the design of the Mach microkernel was better served in architectures on servers. This will involve GNU Hurd in the future.