ppr-outline.rtf

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\f0\fs24 \cf0 What this Presentation Is\
  * A whirlwind guide to practical OS building on x86 architecture\
  * An example of essential kernel code with minimal bloat\
    -- I do not claim this is a fully-featured kernel, though!\
  * An attempt to increase your awareness about what the OS does\
\
What this Presentation is NOT:\
  * A step-by-step how-to on creating an operating system\
  * A guide to operating system design (we may overlook many huge concepts)\
     -- Remember, there are entire course sequences on design alone (much less implementation)\
\
What do I need to know to follow along with you?\
  * The job of an OS is to manage your system's resources and share them based on your need\
      -- Need changes based on system type (i.e. Desktop, real-time systems, etc.).'\
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\cf0   * A kernel is the central component of an operating system. It is, more or less, the program that IS your OS\
  * There are different kernel design methodologies (monolithic kernel vs. microkernel)\
     -- We won't talk about this much more, but you should know these exist\
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\cf0   * Some C and x86 knowledge wouldn't hurt\
\
What tools do I need?\
  * C compiler\
     -- We will use gcc\
  * x86 assembler\
     -- We will, again, focus on gcc but perhaps masm is another good choice\
     -- We get nothing for free (i.e. libc), so writing architecture-dependent code is absolutely essential\
  * An emulator\
     -- On a Linux environment, either QEMU or Bochs work well\
\
Where do I begin?\
  * With what you have!\
    -- We assume you already have a PC which is properly working with an x86 processor\
  * Bootloader\
    -- Initializes CPU and brings it to the kernel to begin execution of OS\
    -- Ok\'85 These can become overly-complicated too for very little pay-off since the advent of grub\
    -- We'll assume we have grub\
  * 
\b Kernel
\b0 \
    -- We only care about the actual kernel for now\
    -- Particularly, the x86 boot code will be our starting point\
  * Caveat: Large programs are complicated\
      -- (Particularly monolithic) kernels tend to have a lot of code\
\
What does grub do for us?\
  * In short, jumps to our kernel code\
  * More specifically:\
    -- Loads kernel from filesystem (based on where you put it during setup)\
    -- Enables protected mode\
    -- Other cool stuff\
  * http://www.gnu.org/software/grub/manual/multiboot/multiboot.html is important here\
\
Great, how do I initialize my kernel?\
  * x86 assembly\
    -- Yes, this is hand-written\
    -- C is good, but it cannot accomplish everything\
  * The Steps:\
    -- Initialize your stack\
    -- Global initialization method at defined segment\
    -- Push necessary information from Machine state (defined in multiboot spec) as arguments\
    -- Disable interrupts\
    -- Call kernel_init (C)\
    -- Re-enable interrupts\
    -- Call kernel_main (C)\
\
kernel_init\
\
So where can I find this information myself?\
  * Manuals\
    -- Intel, ARM, etc. any architecture manual should explain how to initialize the CPU\
  * osdev.org\
  * For design/theory: Tannenbaum writes a good intro book\
}