Why do x86-64 systems have only a 48 bit virtual address space?

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More Related Contents:

  1. Why doesn’t GCC use partial registers?
  2. Why in x86-64 the virtual address are 4 bits shorter than physical (48 bits vs. 52 long)?
  3. How do I achieve the theoretical maximum of 4 FLOPs per cycle?
  4. Why can’t kernel code use a Red Zone
  5. why we can’t move a 64-bit immediate value to memory?
  6. Why does adding an xorps instruction make this function using cvtsi2ss and addss ~5x faster?
  7. Lost Cycles on Intel? An inconsistency between rdtsc and CPU_CLK_UNHALTED.REF_TSC
  8. Difference between x86, x32, and x64 architectures?
  9. Why does Linux favor 0x7f mappings?
  10. Address canonical form and pointer arithmetic
  11. Why does this code execute more slowly after strength-reducing multiplications to loop-carried additions?
  12. Can the simple decoders in recent Intel microarchitectures handle all 1-µop instructions?
  13. Why is the page size of Linux (x86) 4 KB, how is that calculated?
  14. x86 32 bit opcodes that differ in x86-x64 or entirely removed
  15. how are barriers/fences and acquire, release semantics implemented microarchitecturally?
  16. What EXACTLY is the difference between intel’s and amd’s ISA, if any?
  17. What specifically marks an x86 cache line as dirty – any write, or is an explicit change required?
  18. Virtually indexed physically tagged cache Synonym
  19. Enhanced REP MOVSB for memcpy
  20. Floating point vs integer calculations on modern hardware
  21. Why is imul used for multiplying unsigned numbers?
  22. Does an x86 CPU reorder instructions?
  23. On 32-bit CPUs, is an ‘integer’ type more efficient than a ‘short’ type?
  24. Successive sys_write syscalls not working as expected, NASM bug on OS X?
  25. Why flush the pipeline for Memory Order Violation caused by other logical processors?
  26. Performance optimisations of x86-64 assembly – Alignment and branch prediction
  27. Count each bit-position separately over many 64-bit bitmasks, with AVX but not AVX2
  28. Are load ops deallocated from the RS when they dispatch, complete or some other time?
  29. Why use RIP-relative addressing in NASM?
  30. Unexpected page handling (also, VirtualLock = no op?)

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