ProcessAddressSpace.ppt

Process Address Space Outline The Process’s Address Space The Memory Descriptor Memory Regions Page Fault Exception Handler Creating and Deleting a Process Address Space Managing the Heap 1 Process Address Space A kernel function gets dynamic memory The kernel is the highest priority component of the operation system The kernel trusts itself User Mode process get dynamic memory Process requests for dynamic memory are considered nonurgent =defer allocating User programs cannot be trusted = kernel catch all addressing error. Process Address Space Memory region User mode process asks for dynamic memory: It does not get additional page frame. It gets the right to use a new range of linear address, which become part of its address space. This interval is called a memory region. The Process’s Address Space Consists of all linear addresses that the process is allowed to use Each process sees a different set of linear address. Kernel may dynamically modify a process address space by adding or removing intervals of linear address. Memory regions are characterized by an initial linear address, a length, and some access rights. A process gets new memory region user type a command at the console running process load an entirely different program running process perform a “memory mapping” on a file process keep adding data on its user mode stack process create an IPC shared memory region process expand its dynamic area (the heap) System call brk() changes the heap size of process execve() loads a new executable file exit() terminates the current process fork() creates a new process mmap() creates a memory mapping for a file munmap() destroys a memory mapping for a file shmat() creates a shared memory region shmdt() destroys a shared memory region Page fault exception handler Kernel must to identify the memory regions currently owned by a process Those caused by programming errors. Those caused by a missing page. The linear address belongs to the process’s address but t