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Enforcing Modularity

Enforcing Modularity. Client / Service. module per computer module per Virtual computer. Virtual memory. Virtual processor. Kernel. Why VM:. -A can overwrite B’s memory. Mem. code. μProc. Mod A. ST R1,B. data. Mod B. Virtual Memory. VA  VM  Physical. Addr. VA. Address

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Enforcing Modularity

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  1. Enforcing Modularity Client / Service module per computer module per Virtual computer Virtual memory Virtual processor Kernel

  2. Why VM: -A can overwrite B’s memory Mem code μProc. Mod A ST R1,B data Mod B

  3. Virtual Memory VA VM  Physical Addr VA Address Space code Memory code code code Disk

  4. Simplified VM Hardware Mem PA VA VM (MMU) LD VA, R1 μProc. pmar VA PA “page map address reg”

  5. 20 bit 12 bit 212= 4096 words 32 bit VA Page # Offset Page PA Mem Page 4096 bytes

  6. Supervisory Module -Kernel Kernel AS μProc. maps only kernel can change PMAR pmar user / kernel

  7. Supervisor Call -SVC Set U / K  K Set PMAR to kernel map Save PC PC  addr gate SVC gate malloc

  8. Kernel –Trusted intermediary producer (put) Consumer (get) Graphics ES IPC Net Graphics

  9. AS A AS B Memory Code A Code 1 Code B Lib 1 Lib 1,2 Code 2

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