Efficient memory virtualization for cross-ISA system mode emulation

Chao Jui Chang, Jan Jan Wu, Wei Chung Hsu, Pangfeng Liu, Pen Chung Yew

Research output: Chapter in Book/Report/Conference proceedingConference contribution

20 Scopus citations


Cross-ISA system-mode emulation has many important applications. For example, Cross-ISA system-mode emulation helps computer architects and OS developers trace and debug kernel execution-flow efficiently by emulating a slower platform (such as ARM) on a more powerful platform (such as an x86 machine). Cross-ISA systemmode emulation also enables workload consolidation in data centers with platforms of different instruction-set architectures (ISAs). However, system-mode emulation is much slower. One major overhead in system-mode emulation is the multi-level memory address translation that maps guest virtual address to host physical address. Shadow page tables (SPT) have been used to reduce such overheads, but primarily for same-ISA virtualization. In this paper we propose a novel approach called embedded shadow page tables (ESPT). EPST embeds a shadow page table into the address space of a cross-ISA dynamic binary translation (DBT) and uses hardware memory management unit in the CPU to translate memory addresses, instead of software translation in a current DBT emulator like QEMU. We also use the larger address space on modern 64-bit CPUs to accommodate our DBT emulator so that it will not interfere with the guest operating system. We incorporate our new scheme into QEMU, a popular, retargetable cross-ISA system emulator. SPEC CINT2006 benchmark results indicate that our technique achieves an average speedup of 1.51 times in system mode when emulating ARM on x86, and a 1.59 times speedup for emulating IA32 on x86-64.

Original languageEnglish (US)
Title of host publicationVEE 2014 - Proceedings of the 10th ACM SIGPLAN/SIGOPS International Conference on Virtual Execution Environments
PublisherAssociation for Computing Machinery
Number of pages12
StatePublished - Jan 1 2014
Event10th ACM SIGPLAN/SIGOPS International Conference on Virtual Execution Environments, VEE 2014 - Salt Lake City, UT, United States
Duration: Mar 1 2014Mar 2 2014


Other10th ACM SIGPLAN/SIGOPS International Conference on Virtual Execution Environments, VEE 2014
Country/TerritoryUnited States
CitySalt Lake City, UT


  • Cross-ISA dynamic binary translation
  • Embedded shadow page table
  • Hardware MMU
  • Memory virtualization


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