Download Polygonal Broadcast, Secret Maturity and the Firing Sensors

Self-Stabilized Operating System
Shlomi Dolev, BGU
Reuven Yagel, BGU-Rafael
Talk Outline
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Operating Systems & Self Stabilization
OS Research
What can go wrong?
Solutions
Top-down vs. Bottom-up
Minimal OS
Model
Operating Systems & Self
Stabilization
• Initial Goal: Find the means of making the
core(main) components of an OS behave in a SelfStabilized manner.
• Self Stabilization
– Usually Distributed Computing Oriented
– Fair composition [Dolev]
• Operating Systems
– Top-down vs. Bottom-up view
Virtual Machine vs. Resource Manager [Tanenbaum]
– Historical OS main modules: Resource mgmnt: CPU,
Memory, Device Drivers & File System.
OS Research
• Deprecated by industry & hackers
– # of courses in univ.
• Base abstraction for higher abstractions
(middleware, protocol stacks)
• Essential for system reliability.[kernel
projects]
• Operating System.Net (Ideas will move on
to distributed OSs – see sciam article, .Net Framework diagram
What can go wrong?
• Everything!
• Soft errors.
– Approximately 98% of RAM errors are soft
errors.
• Different OS algorithms.
Solutions
• Build on Linux
– Open, Modern, Documented, Unix tradition, Cool…
– But: “Hackered”, Monolithic
– Case study for OS components.
• Hardening
– Security of servers
• SS-Shell
– First try, difficult to prove (show code snippet)
• SONIX
– Reinstalling OS periodically, (Critical Apps?)
Top-down vs. Bottom-up
• Top-down
– Linux kernel: 2M source code lines
– Windows 2000: ~30M
– Shell
• Bottom-Up
– We know what we have!
– Will take some time to become full operational.
MinimalOS
• IA-32 Architecture
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CPU modes
Boot process
Memory map, ROM areas
Coding & Debugging tips
• Watchdog handler
– ROM (Liskov’s article)
– Program Restart (Von Neuman vs. Harvard models?)
• Demonstration
more
• Some model