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User space memory access from the Linux kernel

Aug 15, 2010, 11:03 (1 Talkback[s])
(Other stories by M. Tim Jones)

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"Although the byte may be the lowest addressable unit of memory within Linux®, it's the page that serves as the managed abstraction of memory. This article begins with a discussion of memory management within Linux, and then explores the methods for manipulation of user address space from the kernel.

"Linux memory

"In Linux, user memory and kernel memory are independent and implemented in separate address spaces. The address spaces are virtualized, meaning that the addresses are abstracted from physical memory (through a process detailed shortly). Because the address spaces are virtualized, many can exist. In fact, the kernel itself resides in one address space, and each process resides in its own address space. These address spaces consist of virtual memory addresses, permitting many processes with independent address spaces to refer to a considerably smaller physical address space (the physical memory in the machine). Not only is this convenient, but it's also secure, because each address space is independent and isolated and therefore secure."

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