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Internet Message Format  |  1992-07-30  |  4.7 KB
  1. Path: sparky!uunet!gatech!pitt.edu!gvls1!jabber!candle!root
  2. From: root@candle.uucp (Bruce Momjian)
  3. Newsgroups: comp.unix.internals
  4. Subject: Crash  / Kernel Diagram update
  5. Message-ID: <1992Jul30.035548.727@candle.uucp>
  6. Date: 30 Jul 92 03:55:48 GMT
  7. Organization: a consultant's basement
  8. Lines: 77
  9. X-Newsreader: Tin 1.1 PL4
  10.  
  11. I have updated my previous kernel diagram posting.  Kernel is now
  12. properly spelled, and the file descriptor table's 'crash' command was
  13. improperly labeled.  I use this alow when I know what I want, but can't
  14. remember the commands or how everything fits together.
  15.  
  16.                             *  *  *
  17.  
  18. I wrote a diagram of the major tables in the Unix kernel after reading
  19. Bach's book and using 'crash'.  It is based on my AT&T 386 Unix System
  20. Vr3.1. 'crash' commands are highlighted in upper case.  If anyone has
  21. suggestions or corrections, I would be glad to include them.  It is 57
  22. lines, and may be clearer when printed.
  23.  
  24.  
  25. PROCess               Virual        Segment/Page        Physical
  26.  table                Memory         Descriptor          Memory      
  27.  ______               ______           Tables            ______
  28. |______|             |_text_| \               PDT       |______|\
  29. |______| ------>     |______|  \    SDT       ___   /-->|______| \
  30. |______|             |_data_|   \   ____   ->|___|--    |______|  \     
  31. |______|             |______|    \ |____| /  |___|----->|______|
  32. |______|             |______|     \|____|-   |___|-_    |______|    PFDATa
  33. |______|             |stack_| -->  |____|           \   |______|     ___ 
  34. |______|             |______|     /|____|---         \->|______|    |___|
  35. |______|             |______|    / |____|   |           |______| <- |___|
  36.                  ----|_USER_|   /           | PDT    /->|______|    |___|
  37.                 |    |______|  /            | ___   /   |______|    |___|
  38.                 |    |kernel| /             >|___|-- /->|______|
  39.                 |    |______|/               |___|---   |______|    
  40.                 |                            |___|----->|______|  /
  41.                 |                                       |kernel| /
  42.                 |                                       |______|/
  43.                 | 
  44.      ----------- 
  45.     |
  46.     V 
  47.  
  48. USER File        
  49. Descriptor       FILE          INODE                          
  50.   Table          Table         Table                            Disk
  51.  ______         ______         ______                          ______
  52. |______|------>|______|---_   |______|                        |_boot_|
  53. |______|       |______|    \->|______|--------------------_   |super_|
  54. |______|---_   |______|       |______|                     \->|inode_|
  55. |______|    \->|______|-------|______|----------------------->|inode_|
  56. |______|---_   |______|    /->|______|--------------------_   |inode_|
  57. |______|    \->|______|----   |______|                     \->|inode_|
  58. |______|       |______|--_    |______|                     _->|inode_|
  59.                |______|   \   |______|                    /  -|_free_|
  60.                |______|    \->|______|--------------------  | |inode_|
  61.                |______|       |______|                      | |inode_|
  62.                |______|       |______|                      | |_free_|
  63.                |______|       |______|                      | |_data_|
  64.                                                             | |_data_|
  65.                                                             | |_free_|
  66.                                           Buffer            | |_data_|
  67.                                           Headers           | |_free_|
  68.                                           BUFHDR    BUFFERs | |_free_|
  69.                                           ______       __   | |_data_|
  70.                                          |______|---->|  |<-  |_free_|
  71.                                          |______|      --     |_data_|
  72.                                          |______|      __    _|_data_|
  73.                                          |______|---->|  |<-/ |_free_|
  74.                                          |______|      --     |_free_|
  75.                                          |______|      __     |_data_|
  76.                                          |______|---->|  |<---|_data_|
  77.                                          |______|      --     |_free_|
  78.                                                               |_swap_|
  79.                                                               |_swap_|
  80.                                                               |_swap_|
  81.                                                  
  82.  
  83.  
  84. -- 
  85. Bruce Momjian                      |  830 Blythe Avenue
  86. root%candle.uucp@bts.com           |  Drexel Hill, Pennsylvania 19026 
  87.                                    |  (215) 353-9879(w)  853-3000(h)
  88.