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My kernel has currently the following components :
Correct GDT
Correct IDT
PIC programming
Correct tty driver (almost print functions )

I am trying to write a keyboard handler but I have a problem. I wrote an asm IRQ function which call my C handling function.
I wrote a keyboard init funtion just with some simple instructions to initialize my keyboard buffer :
[pre]current = 0;
last = 0;[/pre]
where 'current' and 'last' are unsigned char I will use to remember the position in the keyboard buffer.

This code works perfectly on two machines (P166 & 386) but reboots two others (P90 & PIII667). I found out that it was the second instruction ('last = 0;') that causes this.

I also tried to call a dummy function within my keyboard init function instead of the two instructions above, and it reboots too.

Can anyone help me ?

Maybe if I saw your source I could help...

this sounds like the stack is too small or something alike ...
Maybe you also have a problem with your ISR save/restore code.

Here is a working Key hander ( I got some of it from curfer(forgot his exact screenname) )

Needs to be in asm:

EXTERN KeyHan ; Your Key handling function
GLOBAL IRQ1
IRQ1:
pusha
call KeyHan
mov al, 0x20
out 0x20, al
popa
IRET

In your C code:

void KeyHan
{
// stuff... and don't use outportb( 0x20, 0x20 );
// since the other function does that for you.

int key;
key = inportb( 0x60 );
}

Thanks a lot for these hints. I am gonna make some test and will report the results here this evening.

My kernel reboots when I call my C keyboard handler in my irq1 asm function.
So instead of calling it, I wrote on the screen the address of the handler. I got 12892.
Then I added a instructions in my C kernel body function to wrote the address of my keyboard handler, and I got 12896.

Shouldn't I have the same two addresses ?
Is this my problem ?

Here's my irq1 (n)asm functions :
[pre]EXTERN keyboard

irq1:
cli
push eax
call keyboard
mov al,0x20
out 0x20,al
pop eax
sti
iret[/pre]

and here's my C keyboard handler function :
[pre]extern void putchar(unsigned char);

void keyboard(void)
{
unsigned char inv;

inv=inb(0x60);
putchar('.');
return;
}
[/pre]

Here's a part of my C kernel body function
[pre]// Init PIC
outb(0x20,0x11);
outb(0x21,0x20);
outb(0x21,0x4);
outb(0x21,0x1);
outb(0x21,0xFD);
outb(0xA0,0x11);
outb(0xA1,0x70);
outb(0xA1,0x2);
outb(0xA1,0x1);
outb(0xA1,0xFF);
[/pre]

'inb' and 'outb' are simple asm functions to get (set) a byte from (to) a port.

This sequence causes the computer to reboot when I press a key
What have I made wrong ?

Remove the "return" in the keyboard() function.

Why CLI in the IRQ1 function?

And use pusha instead of push eax.

Removing the 'return' didn't change anything

I put a 'cli' in my irq1 function because I think that it may be more careful to unable other interruptions when you are just processing one. (imagine a timer interruption while you are processing a key press...)

You have to save all registers and load them with a save selector...
try something like this:

Pini, your handler is good(in nasm): But maby your IDT is wrong?

I made a few tests and here is what I found out :

when I make a dummy keyboard handler like this :
[pre]void keyboard(void)
{
}
[/pre]
it works, but when I insert this instruction :
[pre]void keyboard(void)
{
unsigned char value;

value=inb(0x60);
}
[/pre]
it reboots.

What does this mean ? I am completly lost :-\

I don't think it comes from my IDT, because I made a printing test with the timer interrupt and ... well, my keyboard handler works on other machines and with bochs 2.0.

CLIing ... won't that stop your PIT and mess up your OS when you come to multi tasking?