This preview shows page 1. Sign up to view the full content.
Unformatted text preview: itrary physical pages located anywhere in physical memory. Because of the way page tables work, there is no need for the operating system to locate contiguous pages of physical memory. The pages can be scattered randomly in physical memory. 10.4.4 Simplifying Loading
Virtual memory also makes it easy to load executable and shared object ﬁles into memory. Recall that the .text and .data sections in ELF executables are contiguous. To load these sections into a newly created process, the Linux loader allocates a contiguous chunk of virtual pages starting at address 0x08048000, 496 CHAPTER 10. VIRTUAL MEMORY marks them as invalid (i.e., not cached), and points their page table entries to the appropriate locations in the object ﬁle. The interesting point is that the loader never actually copies any data from disk into memory. The data is paged in automatically and on demand by the virtual memory system the ﬁrst time each page is referenced, either by the CPU when it fetches an instruction, or by an executing instruction when it references a memory locati...
View Full Document
This note was uploaded on 09/02/2010 for the course ELECTRICAL 360 taught by Professor Schultz during the Spring '10 term at BYU.
- Spring '10
- The American