Abstract
To provide modularity and performance, operating system kernels should have
only minimal embedded fucntionality. Today\'s operating systems are so large
, inefficient and , most importantly, inflexible. In our view, most
operating system performance and flexibility problems can be eliminated by
pushing the operating system interface lower. Our goal is to put
abstractions traditionally implemented by the kernel out into user-space,
where user-level libraries and servers abstract the exposed hardware
resources. To achieve this goal, we have define a new operating system
structure, exokernel, that safely exports the resources defined by the
underlying hardware. TO enable applications to benefit from full hardware
functionality and performance, they are allowed to download additions to the
supervisor-mode execution environment. To guarantee that these extensions
are safe, techniques such as code inspection, inlined cross-domain procedure
calls, and secure languages are used. To test and eveluate exokernels and
their customization techniques a prototype exokernel, Aegis, is being
developed.
