Last Evaluation

Yang YU (yyu@cs.ucsd.edu)
Mon, 05 Jun 2000 22:11:52 -0700

1. SPIN
Summary: SPIN is an extensible operating system that can be
dynamically specialized to meet the needs of individual
applications.
Goal: provides extensibility, safety, and good performance, but
also customizable in that it provides low-cost, fine-grained, protected
access to OS resources.
Approach: Co-location ,Enforced modularity,Logical protection
domains,Dynamic call binding
Conclusion:
Spin seems to offer good performance, extendibility, and fine grain
access to resources while maintaining safety. This flexibility is
impressive, and
clearly a win for applications with specific needs not addressed
sufficiently by general operating systems.
These features come with a price, however - the system depends very
heavily upon Modula 3, which may impose limitations upon application
writers and present hidden dangers.

2. Exokernel
Summary: Kernel can be made small and efficient by making it as
close to hardware as possible
Motive:Traditional OS architectures are slow and too restrictive:
they constrain applications to using a single interface
Approach:
Exports instruction set plus system calls to encapsulate
privileged instructions
Secure bindings for reservation of resources by applications
Application-visible revocation and abort protocols for resources

Protected control transfer between applications as a basis for
IPC, as with Lightweight Remote Procedure Call
Packet filters and Application-specific Secure Handlers to allow
general processing on receipt of packets

--
Yang Yu
Department of Computer Science and Engineering
University of California, San Diego