[MUD-Dev] OS Inspiration

Phillip Lenhardt philen at funky.monkey.org
Sat Jan 1 17:49:22 New Zealand Daylight Time 2000


I myself don't have the ability to apply this code and its ideas to MUD
design, but I feel EROS (http://www.eros-os.org/) has a lot 
to offer the MUD developer, including:


Pure Capability Architecture

    EROS is a pure capability system. Authority in the system is conveyed
    exclusivly by secure capabilities, down to the granularity of
    individual pages.
                  
Orthogonal Global Persistence

    All user state, including both data and running programs, are
    transparently saved on a periodic basis. In the event of system
    failure processes are resumed as of the last checkpoint. No special
    action or programming on the part of the application is required.
                  
Kernel Threads

    The EROS kernel itself is implemented using multiple kernel-mode
    threads. This improves the performance of EROS drivers, makes them
    simpler to code, and greatly simplifies the design of the kernel. In
    addition, it enables selected kernel functionality to be preempted by
    higher priority user activities.

Security
                                           
    Because EROS processes are persistent, processes can hold authorities
    in their own right rather than inheriting them from the user. This
    enables a rich variety of options for security and access control that
    are impossible in systems lacking persistent processes.

"Stateless" Supervisor

    While the EROS kernel caches user state in a variety of ways for the
    sake of performance, essentially all of the state maintained by the
    kernel is derived from user-provided information. Only two pieces of
    kernel state are saved in a persistent snapshot: the list of running
    threads and the directory of objects in the checkpoint log.

Deadlock-Free Supervisor

Minimal Kernel
            
    The EROS kernel contains relatively little code. The current
    (incomplete) system is 24.3k of binary code. The final,
    non-distributed kernel is expected to weigh in at 50k to 60k on
    completion. The latter number includes critical drivers and the
    persistence manager. No size tuning has been done.

Distribution

    EROS provides all of these facilities, including orthogonal
    persistence, across a cluster of machines.



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