Programming Guid


Author : Adham Helal
Doc by : Adham Helal
Revision : NONE
Prog lang : INFO PAGE
Pref-Com : NONE
last update: 07-07-02

This Paper talks about the boot process in genral.

TiTan boots on number of steps it might be diffrent from one installition to another but basicly this is the normal way
1- Ploader
2- sloader
3- kernel init
4- TiTan kernel

lets examine a Hard Disk with two operating systems in the first partion we have linux and in the second we have TiTan

|          |                                 |                  |
| MBR|  1- Linux                 | 2-TiTan    |
|_____|________________ |_________|
0      512                     1024000         1040000

This example uses just imaginary number and i use linear addressing( in real HD you would have Heads, Sectors, Cyl )

So our MBR should have 2 things number one the partion Table which describes partion locations and some info on the partions i.e. File system ID. Number 2 a Boot Loader in our case ploader. when the computer loadeds you will be asked which OS you want to load if you say linux what really happens is that ploader loads the first 512 byte from partion 1which contains a loader called Lilo (linux loader) in this case lilo will then handle the loading process by loading the linux kernel. So ploader is just a chain loader. ploader itself can't load any OS by any means it's job is to load another loader.

Things run this way because there are big differences in the way every OS boots for example linux loads in a diffrent way then windows 98. Even windows 98 loads differently then windows NT. this is way the boot process is separated into steps.

Getting Back to our Example lets say you chose to load TiTan what will happen is that ploader will load the first 512 bytes (sloader ) of the second partion into the memory and jumps there. Once the sloader is running it will take care of loading another loader but this time a more Enhanced loader called the kernel init. Kernel init will then load the TiTan kernel

As you can see the boot process is not complicated but it gets ugly some times. We still do have 1 problem though in the above discreption. when the ploader loads the sloader it should send some argument the problems is i can't find out is there any standers to send the date with.
I am currently reading and as soon as i get this info i will fix it.

This was just an overview on the boot process.

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