[CSE]  Advanced Operating Systems 
  COMP9242 2002/S2  		UNSW
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Next: LLinux Performance Up: 05-uk Previous: -kernel Design Principles

Subsections

Case in Point: L\(\!^4\)Linux [Härtig et al. 97]


  • Port of Linux kernel to L4 (like Mach Unix server)
    • single-threaded (for simplicity, not performance)
    • is pager of all Linux user processes
    • maps emulation library and signal-handling code into AS
    • server AS maps physical memory (& Linux runs within)
    • copying between user and server done on physical memory
      • use software lookup of page tables for address translation
  • Changes to Linux restricted to architecture-dependent part
  • Duplication of page tables (L4 and Linux server)
  • Binary compatible to native Linux via trampoline mechanism
    • but also modified libc with RPC stubs

Signal delivery in L\(\!^4\)Linux

h+_97_f3

  • separate signal-handler thread in each user process
    • server IPCs signal-handler thread
    • handler thread ex_regs main user thread to save state
    • user thread IPCs Linux server
    • server does signal processing
    • server IPCs user thread to resume


Gernot Heiser 2002-08-28