The VMTaskSupport interface helps emulate a Mach virtual memory environment. The SPIN Space extension interface does support inheritance or allocation at an unspecified address. The VMTaskSupport interface provides this functionality.
The VMTaskSupport module maintains a data structure of all the user-space memory allocation. The data structure is a table of address space records. Each address space record contains a table of allocations in its space as well as its current allocation pointer. Each allocation field records the begin address and size of the allocation, an inheritance attribute, and a SPIN capability for that region of virtual memory.
Each user-space allocation must be registered in the allocation table. If the location for the allocation is unspecified, the current allocation pointer for the address space is used and then incremented. When a new address space is created, it may inherit from an existing address space. In this case, the allocation table for the existing space is traversed, and all regions are aggressively copied into the new address space. Sharing and copy-on-write are not implemented.
The VMTaskSupport interface is VMTaskSupport.i3.
Note: VMTaskSupport was made obsolete by the Address Space extensions.
ddion@cs.washington.edu