Lesson plan
Capability-based addressing
In computer science, capability-based addressing is a scheme used by some computers to control access to memory as an efficient implementation of capability-based security. Under a capability-based addressing scheme, pointers are replaced by protected objects (named capabilities) which specify both a location in memory, along with access rights which define the set of operations which can be carried out on the memory location. Capabilities can only be created or modified through the use of privileged instructions which may be executed only by either the kernel or some other privileged process authorised to do so. Thus, a kernel can limit application code and other subsystems access to the minimum necessary portions of memory (and disable write access where appropriate), without the need to use separate address spaces and therefore require a context switch when an access occurs.
Article summary
In computer science, capability-based addressing is a scheme used by some computers to control access to memory as an efficient implementation of capability-based security. Under a capability-based addressing scheme, pointers are replaced by protected objects (named capabilities) which specify both a location in memory, along with access rights which define the set of operations which can be carried out on the memory location. Capabilities can only be created or modified through the use of privileged instructions which may be executed only by either the kernel or some other privileged process authorised to do so. Thus, a kernel can limit application code and other subsystems access to the minimum necessary portions of memory (and disable write access where appropriate), without the need to use separate address spaces and therefore require a context switch when an access occurs.
Key claims
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Discussion questions
- Summarise the article in your own words. Which single claim would you verify first, and why?
- Which claim in this article is most likely to be revised as the sources update? How would you check its current status?
- If two sources disagreed about one of these facts, what would you need in order to trust one over the other?
Bibliography
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Key claims and bibliography are generated from the same tracked claims and sources as the article page.