Index

1. Introduction to microkernel development

• aim of this section:
  • understand more about the development host you will be using to build your microkernel
  • go to the GNU/Linux laboratory and put this lecture into practice by implementing a small utility in C

2. Guide to using GNU/Linux

• the machines in our laboratories have the ability to run Windows or GNU/Linux
  • these machines default to running Windows
• if you see Windows running and you want to use GNU/Linux
  • must reboot Windows gracefully
  • watch it reboot

3. Guide to booting GNU/Linux

• after shutting down Windows wait for the redhat lilo prompt
  • then cursor down to Linux and press return
  • you must catch this within 10 seconds or it will automatically boot into Windows
• wait 15 seconds and the graphical login screen should appear

4. Guide to using GNU/Linux

• at the graphical login prompt type in your user name and password
• your first task should be to give yourself a different password, by starting an xterm and running the program

• yppasswd

5. Introduction to GNU/Linux

• use netscape or IE to download lab1
• extract this by
  • opening an xterm
  • and using

• tar xvf lab1.tar
  cd lab1
  ls -l

• which copies all files related to tutorial 1 into your own file area
  

6. Tutorial 1

• ls can be used to examine the files:

• bash$ ls -la
  total 9
  -rw-r--r--   1 gaius    118 Jun 26 09:57 .gdbinit
  -rw-r--r--   1 gaius    775 Sep 28 12:54 Debug.def
  -rw-r--r--   1 gaius   1274 Sep 28 12:58 Debug.mod
  -rw-r--r--   1 gaius   1274 Sep 28 12:58 Debug.c
  -rw-r--r--   1 gaius    144 Sep 28 12:54 ass1.mod
  -rw-r--r--   1 gaius      0 Sep 28 12:54 depend
  -rw-r--r--   1 gaius   4592 Aug  1 16:17 make.rules
  -rw-r--r--   1 gaius   1482 Sep 28 12:54 makefile

7. Tutorial 1: implementing a debugging facility

• your task is to complete the C file Debug.c

8. Simple editing commands

• there are many editors available under GNU/Linux
• one popular editor is xemacs
• use the menu, however 4 extra useful commands are:

  

• Where ^c means press control C and ^x means press control x.
  

9. Compiling and Linking

• using an xterm, type:

• cd lab1
  make c

10. Compiling and Linking

• before you start developing your program you should place a blank floppy disk into drive a:
• to compile you can either run an xterm and type:

• make

• or if you are using the xemacs editor then you can compile by using the menu
  

11. Compiling and Linking

• if your program fails to compile the compiler will generate an error message indicating the file, line number and why it failed
  • if you are compiling from within xemacs (by using the pull down menu) then you can tell xemacs to go to the next error by typing ^x‘
• after your program successfully compiles and links run an xterm and type:

• make bootdisk
  dd if=image of=/dev/fd0 bs=18k

• this will place your code onto a floppy disk
  • note any previous data on your floppy disk will be totally trashed
    

12. Running your microkernel

• once the code is on the floppy disk
  • microkernel boot disk
• need to reboot another PC to execute the microkernel
• please reboot machines gracefully

13. Debug.c pseudo code

• void Debug_DebugString
                (char *a, unsigned int high)
  {
     /* foreach character in "a"
            if the sequence "\" "n" is seen
            then
               generate a newline
            else
               print character to the screen
            end
        end  */
  }

14. Debug.c

• #define ASCII_cr   ’\r’
  #define ASCII_lf   ’\n’
  #define ASCII_null ’\0’
  
  
  /*
   *  WriteLn - writes a carriage return and a
   *            newline character.
   */
  
  
  static void WriteLn (void)
  {
    Scn_Write(ASCII_cr);
    Scn_Write(ASCII_lf);
  }

15. Function DebugString

• /*
   *  DebugString - writes a string to
   *                the debugging device (Scn_Write).
   *                It interprets \n as
   *                carriage return, linefeed.
   */
  
  void Debug_DebugString (char *a,
                          unsigned int high)
  {
    OnOrOff      OldInterruptState
                   = SYSTEM_TurnInterrupts(Off);
    unsigned int n = 0;
  
    /* your code needs to go here */
  
  
    OldInterruptState
         = SYSTEM_TurnInterrupts(OldInterruptState);
  }

• remember we must stop writing characters either
  • when we spot a ASCII_null in the array or
  • our index exceeds, high.

Index

This document was produced using groff-1.19.