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2012-04-10

Virtual Memory

  • 有 code 有真相 
  • Page Table entry (PTE)

Page Table Width: 10 bit + 10 bit + 12 bit
- 10 bit 使用較少量的記憶體

修改過的 QEMU 提供 "info pg" monitor 指令,可交叉觀察 CR3 設定前後的 page 變化,檢驗首個與末個 page

Challenge! Extend the JOS kernel monitor with commands -> 開發 in-kernel debugger 

"follow the bouncing kernel" on stackoverflow
  • method 1 - swap in/out to other storage

boot_alloc

TDD (Test-Driven Development) in JOS
assert() supported in patched QEMU

Hawx

page_alloc() -- the page reference count pp_ref
page_insert()

pp_ref (reference count)

=> hawx's version

page_table 3

  • page 1  1
  • page 2  1
  • page 3  1


page_table 4

  • page 1  1
  • page 2  1
  • page 3  1

=> MIT JOS

page_table 1

  • page 1   x
  • page 2   x
  • page 3   x

How to start to write labs?

  • check homework next lecture
  • reference the check code for grade calculation

PDOS paper

The exokernel approach to extensibility (panel statement)

Related: http://hypervisor.org/

Ben

Question: 目前兩週舉行一次會不會太頻繁?

  • Ans: 比較難的lab分成兩次。

memory verifier -- magic 1 + [mem] + magic 2

  •   kernel built-in
  • gcc library - LD_PRELOAD=./mem_verifier_library.so     (replace malloc , dealloc, free ..)
  • a tool: valgrind
    • Android 4.0 內建 valgrind: external/valgrind

main/VEX/ => 模擬 host ISA 的行為來作 memory debugging

libvex -> library for dynamic binary instrumentation

Related paper: Bounds Checking with Taint-Based Analysis

    http://cseweb.ucsd.edu/~wchuang/HiPEAC-07-TaintBounds.pdf

Jserv

  1. OSDC.tw 2012 介紹 ARM virtualization -- http://osdc.tw/schedule
  2. Rework Plan 9's protocol to fit the requirements of new products.
  3. Linux community: http://www.svlug.org/
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