Operating Systems,Unix [closed]

It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably开发者_开发问答 answered in its current form. For help clarifying this question so that it can be reopened, visit the help center. Closed 11 years ago.

The process is in either user mode or kernel mode based on this fact i want to ask that how process in user mode can map virtual address to physical address when it has no access to uarea.

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A user-mode process isn't supposed to know about physical addresses. That's the whole point of virtual memory.

EDIT: It seems you're asking how a userspace program knows where to put it's data. It doesn't. It pretends it has the whole address space (0-4GB on x86) and the Operating System does whatever address translation is necessary to let the process pretend that.