Memory Management

In Memory management, virtual memory is highly used concept.
Generally Virtual memory is per process but not for whole system. Pagetables, Translation lookaside buffers etc are swapped when a context switching of process happens.

In Linux:
Approximately the first two megabytes of physical memory are reserved
– For the PC architecture and for OS text and data, the rest is available for paging
• The logical address space of a process is divided into two parts
– 0x00000000 to PAGE_OFFSET-1 can be addressed in either
user or kernel mode
– PAGE_OFFSET to 0xffffffff can be addressed only in
kernel mode
– PAGE_OFFSET is usually 0xc00000000