Archive of UserLand's first discussion group, started October 5, 1998.

if Linux isn't cutting-edge enough for you...

Author:Seth Gordon
Posted:10/28/1999; 10:20:36 AM
Topic:if Linux isn't cutting-edge enough for you...
Msg #:12464
Prev/Next:12463 / 12465

A research OS that used to be a Ph.D. dissertation, EROS (the Extremely Reliable Operating System), is now available under the GPL. (It used to be under a Mozilla-like license.)

It's still very much a research system -- you have to build it under Linux and then install it into a separate partition, and there aren't many applications available. However, it has some very interesting features; the ones most interesting to me (as an amateur hacker) are:

  1. For security, it uses "capabilities". A capability is a sort of key; every object in the system has several capabilities associated with it, and each capability represents things that can be done. (For example, "read permission" and "read/write permission" on a file would be represented by separate capabilities.) This allows for fine-grained security that you can't get with the user- and group-based access control.
  2. From most applications' point of view, there is no distinction between data in RAM and data saved to disk. There are just pages of address space. The OS keeps track of which pages need to be swapped in and out.
  3. About every five minutes, the OS "checkpoints", saving the whole state of the system to disk; if you unplug the machine and plug it in again, every process just starts running again from the last checkpoint.
  4. The time to process a system call (e.g., creating a new process) in EROS comparable to the time it takes in Linux -- so you can use all the above features without having your applications suffer a performance hit.

The implications for developing Internet-related applications are left as an exercise for the reader. Perhaps some people who actually know how to write such applications can mosey over to EROS's Web site (warning: response is kind of slow right now) and come back with their comments.

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