Question

I am using a N450 board (Intel Atom), Eclipse as IDE, I am coding in C and AT&T for assembly code.

I try to use APIC Timer on periodic mode and with my ISR_55

InitTickISR:
    push    %ebp    //save the context to swith back
    mov     %esp,%ebp

// Divide Configuration Register (for Timer) addr : FEE0 03E0 <-
    movl    $0xFEE003E0, %eax
    movl    $0x3, (%eax)//0x3:Divided by 16, 0xA :divide by 128

// Initial Count addr : FEE0 0380 <- 0x1000
    movl    $0xFEE00380,%eax
    movl    $0x100, (%eax)

// LVT(Local Vector Table) Timer Register (FEE0 0320H) -- Interrupt 0x55
    movl    $0xFEE00320, %eax
    movl    $0x20055, (%eax)//2: periodic mode, 01:one shot
                            //55: interruption
// Enable local APIC addr : FEE0 00F0 <- 0x100
    movl    $0xFEE000F0, %eax
    movl    $0x100, (%eax)    

    pop     %ebp //Return to the calling function
    ret

the ISR is just like that for now :

isr0x55:
    cli
    sti
    iret

i can see the timer count changes value (I check the register 0xFEE00390), but the ISR is never called (I have put a break point in it !!!).

Did i forget to set something ? how can I be sure that every thing is set correclty ?

Answer 1

I have resolved the issue by using the EOI register to reset the ISR register.