In computer science, a single address space operating system (or SASOS) is an operating system that provides only one globally shared address space for all processes. In a single address space operating system, numerically identical (virtual memory) logical addresses in different processes all refer to exactly the same byte of data.[1]

Single address-space operating systems offer certain advantages. In a traditional OS with private per-process address space, memory protection is based on address space boundaries ("address space isolation"). Single address-space operating systems use a different approach for memory protection that is just as strong.[2][3] One advantage is that the same virtual-to-physical map page table can be used with every process (and in some SASOS, the kernel as well). This makes context switches on a SASOS faster than on operating systems that must change the page table and flush the TLB caches on every context switch.

SASOS projects include the following:

See also


  1. ^ Eric J. Koldinger; Jeffrey S. Chase; Susan J. Eggers (September 1992). "Architecture support for single address space operating systems". ACM SIGPLAN Notices. 27 (9): 175–186. doi:10.1145/143371.143508.
  2. ^ Tim Wilkinson; Kevin Murray; Stephen Russell; Gernot Heiser; Jochen Liedt (13 November 1995). "Single Address Space Operating Systems" (PDF). Section 2: "Memory Protection". CiteSeerX ((cite journal)): Cite journal requires |journal= (help)
  3. ^ Jeffrey S. Chase; Henry M. Levy; Michael J. Feeley; Edward D. Lazowska (November 1994). "Sharing and protection in a single-address-space operating system" (PDF). ACM Transactions on Computer Systems. 12 (4): 271–307. CiteSeerX doi:10.1145/195792.195795.
  4. ^ Michael Golm; Meik Felser; Christian Wawersich; Jürgen Kleinöder. "The JX Operating System" (PDF).
  5. ^ "OS-9 Technical Manual" p. 29 quote: "all user tasks share a common address space."
  6. ^ Kevin Boos, Namitha Liyanage, Ramla Ijaz, and Lin Zhong. "Theseus: an Experiment in Operating System Structure and State Management". 2020.
  7. ^ "Torsion Operating System". quote: "Torsion ... a single address space multitasking operating system with transparent data persistence."
  8. ^ "Vxworks Tutorial" quote: "In vxworks ... all application tasks share the same address space [unless the] optional tool named VxVMI [has been] used to allow each task to have its own address space."