PIT is not responding...

[eXeCuTeR]

In my kernel, I've installed the GDT and the IDT and they both react and work just fine.
I've added IRQs handling (i've remapped the iqrs to the 32-47th interrupts) to my IDT and tried to test it using the first channel of the PIT (which is the timer) and somehow it doesn't respond (the interrupt handler isn't even called from assembly)

Here are the sources:

this the interrupt handler:

Code: Select all

void interrupt_handler(registers_state registers)
{
	change_bg_color(0x09);
	change_foreground_color(0x0F);
	screen_clear();
	puts("Interrupt handling in action...\n");
	
	if(registers.interrupt_number < 32) // if it's an exception
	{
		puts(exceptions_names[registers.interrupt_number]);
		puts(" Exception has been caught!\n");
		puts("Halting the system...");
		for(;;) ;
	}
	
	if(registers.interrupt_number >= 32 && registers.interrupt_number <= 47) // IRQ
	{
		puts("An IRQ has been caught!\n");
		if(registers.interrupt_number >= 40) // the IRQ came from the slave
			outport(0x0A, 0x20); // sending an EOI (end of interrupt) to the slave
		outport(0x20, 0x20); // sending an EOI to the master anyways
		if(int_handlers[registers.interrupt_number] != 0) // if it's not NULL
			int_handlers[registers.interrupt_number](registers);
	}
}

here's the assembly code which is supposed to be calling interrupt_handler when an IRQ/exception is fired.

Code: Select all

%macro ISR_NON_ERR_CODE 1
	global exception%1
	exception%1:
		cli ; we don't want anyone to interrupt us
		push 0 ; we want to keep up on an aligned stack frame
		push %1 ; interrupt number
		jmp call_isr
%endmacro

%macro ISR_DROP_ERR_CODE 1
	global exception%1
	exception%1:
		cli
		push %1
		; push ERR_CODE (an error code is pushed already)
		jmp call_isr
%endmacro

%macro IRQ 2
	global IRQ%1
	IRQ%1:
		cli
		push 0
		push %2
		jmp call_isr
%endmacro

ISR_NON_ERR_CODE 0
ISR_NON_ERR_CODE 1
ISR_NON_ERR_CODE 2
ISR_NON_ERR_CODE 3
ISR_NON_ERR_CODE 4
ISR_NON_ERR_CODE 5
ISR_NON_ERR_CODE 6
ISR_NON_ERR_CODE 7
ISR_DROP_ERR_CODE 8
ISR_NON_ERR_CODE 9
ISR_DROP_ERR_CODE 10
ISR_DROP_ERR_CODE 11
ISR_DROP_ERR_CODE 12
ISR_DROP_ERR_CODE 13
ISR_DROP_ERR_CODE 14
ISR_NON_ERR_CODE 15
ISR_NON_ERR_CODE 16
ISR_NON_ERR_CODE 17
ISR_NON_ERR_CODE 18
ISR_NON_ERR_CODE 19
ISR_NON_ERR_CODE 20
ISR_NON_ERR_CODE 21
ISR_NON_ERR_CODE 22
ISR_NON_ERR_CODE 23
ISR_NON_ERR_CODE 24
ISR_NON_ERR_CODE 25
ISR_NON_ERR_CODE 26
ISR_NON_ERR_CODE 27
ISR_NON_ERR_CODE 28
ISR_NON_ERR_CODE 29
ISR_NON_ERR_CODE 30
ISR_NON_ERR_CODE 31
IRQ 0, 32
IRQ 1, 33
IRQ 2, 34
IRQ 3, 35
IRQ 4, 36
IRQ 5, 37
IRQ 6, 38
IRQ 7, 39
IRQ 8, 40
IRQ 9, 41
IRQ 10, 42
IRQ 11, 43
IRQ 12, 44
IRQ 13, 45
IRQ 14, 46
IRQ 15, 47

extern interrupt_handler
global call_isr
call_isr:
	pusha
	mov ax, ds
	push eax
	mov ax, 0x10
	mov ds, ax
	mov fs, ax
	mov gs, ax
	mov es, ax
	mov ss, ax
	call interrupt_handler
	pop eax
	mov ds, ax
	mov fs, ax
	mov gs, ax
	mov es, ax
	mov ss, ax
	add esp, 8 ; interrupts number and error code
	popa
	sti ; enable interrupts from here
	iret

timer.c:

Code: Select all

#include "prototypes.h"

unsigned int ticks = 0;

void tick(registers_state registers)
{
	ticks++;
	puts("Whoops!\n");
	/*if(ticks == 50)
	{
		puts("That's enough for me...\n");
		int_handlers[32]/*IRQ #0*/ = 0;
	}*/
}

void initialize_timer(unsigned int frequency)
{
	register_int_handler(32/*IRQ #0*/, &tick);
	unsigned int divisor = 1193180 / frequency;
	outport(0x43, 0x36);
	unsigned char l = divisor & 0xFF;
	unsigned char h = (divisor >> 8) & 0xFF;
	
	outport(0x40, l);
	outport(0x40, h);
}

and inside the main function I call initialize_timer(60) and the PIT is not responding (the interrupt_handler function isn't even called!)

What am I doing wrong?

[gzaloprgm]

Maybe you forgot to enable hardware interrupts
asm volatile("sti"); maybe?

Cheers,
Gonzalo

[System123]

Everything looks fine. All i can think is that u didnt enable interrupts after you set up the gdt, idt, isr, irq. The fact the handler never gets called tells me that is the problem.

[eXeCuTeR]

Damn it! didn't expect this, hehe
Hmm, after I enable interrupts I keep getting Division by Zero exception (EIP = 1048613 dec = 0x100025)

Any ideas why?

[negcit.K]

Damn it! didn't expect this, hehe
Hmm, after I enable interrupts I keep getting Division by Zero exception (EIP = 1048613 dec = 0x100025)

Any ideas why?

that's depends where the kernel location you move and exactly the location invoking the fault.

[negcit.K]

wow, i can reply again!
last days i tried to post a reply or even a topic, but it always say that my ip is in blacklist, so blocked .
but today i can do it again, anybody has ideas?

[eXeCuTeR]

Nevermind, got it working now.