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Large Physical Memory (LPM) means that the system can utilize up to 64GB of physical memory. The kernel uses the Physical Address Extension (PAE) mode of the processor when operating with more than 4GB of memory.
The kernel supports up to 8GB of general purpose memory, and also supports dedicated memory. Dedicated memory is memory that is set aside at system initialization time for use by specific shared memory facilities. This memory cannot be used by the system for any other purpose.
Dedicated memory includes Page Size Extension (PSE) Shared Memory (SHM), Dynamic Shared Memory (DSHM) and Fine-Grained Affinity Shared Memory (FGA-SHM). PSE SHM allows processes that use SHM and request a segment (1MB or greater) to improve performance by using 4MB pages (2MB pages with PAE mode). DSHM allows processes to create shared memory segments that are up to 63GB in length and to circumvent the 3GB constraint of user virtual addresses by allowing an application dynamically to create the mappings between its virtual address space and the shared memory object's pages, as needed.