Opal
The Opal project is exploring a new operating system structure,
tuned to the needs of complex applications, such as CAD/CAM, where
a number of cooperating programs manipulate a large shared
persistent database of objects. In Opal, all code and data exists
with in a single, huge, shared address space. The single address
space enhances sharing and cooperation, because addresses have a
unique (for all time) interpretation. Thus, pointer-based data
structures can be directly communicated and shared between programs
at any time, and can be stored directly on secondary storage
without the need for translation. This structure is simplified by
the availability of a large address space, such as those provided
by the DEC Alpha, MIPS R4000, HP/PA-RISC, and IBM RS6000.
Protection in Opal is independent of the single address space;
each Opal thread executes within a protection domain that
defines which virtual pages it has the right to access. The rights
to access a page can be easily transmitted from one process to
another. The result is a much more flexible protection structure,
permitting different (and dynamically changing) protection options
depending on the trust relationship between cooperating parties. We
believe that this organization can improve both the structure and
performance of complex, cooperating applications.
An Opal prototype has been built for the DEC Alpha platform on
top of the Mach operating system.
- Information Sources
- Faculty Members
- Current Graduate Students
- Related Information
For more information on the OPAL project, please contact
levy@cs.washington.edu.
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- H. Levy / M. Kadenko, 2/4/97