RE: KVM's PIT and PIC programming question

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Isn't by default PIT and PIC are initialized in Kernel? Is something more needed on top of it?

I have enable PIC interuupt using following code :-

> PIC Programming
> ;; PIC
>    mov  al, #0x00
>    out  0x21, AL ;master pic: all IRQs unmasked
>    out  0xA1, AL ;slave  pic: all IRQs unmasked


Also, I wonder if LAPIC need to be configured and initialized properly. I don't want to use LAPIC, can it be disabled in KVM. I am just using one VCPU.

-Thanks
Abhishek

 

-----Original Message-----
From: Avi Kivity [mailto:avi@xxxxxxxxxx] 
Sent: Thursday, August 20, 2009 1:29 AM
To: Saksena, Abhishek
Cc: kvm@xxxxxxxxxxxxxxx
Subject: Re: KVM's PIT and PIC programming question

On 08/20/2009 12:26 AM, Saksena, Abhishek wrote:
> Hi Guys,
> I am writing very simple bios for KVM (not using Qemu but creating a simple io device models around KVM). I am having trouble in receiving regular Timer interrupts after programming PIT.
>
> I think I have enabled PIC and PIT correctly using following code:-
>
> PIC Programming
> ;; PIC
>    mov  al, #0x00
>    out  0x21, AL ;master pic: all IRQs unmasked
>    out  0xA1, AL ;slave  pic: all IRQs unmasked
>
>
> PIT Programming
>
> and also enable PIT to genrate regular timer interruput
>
> SET_INT_VECTOR(0x08, #0xF000, #int08_handler)
>    mov al, #0x34 ; timer0: binary count, 16bit count, mode 2
>    out 0x43, al
>    mov al, #0x00 ; maximum count of 0000H = 18.2Hz
>    out 0x40, al
>    out 0x40, al
>
>
> PIT Timer ISR code
>
> Timer ISR code
>
> ;---------
> ;- INT08 -
> ;---------
> .org 0xfea5 ; INT 08h System Timer ISR Entry Point
> int08_handler:
>    sti
>    push ax
>    push ds
>    mov ax, #0x0040
>    mov ds, ax
>    mov ax, 0x006c ; increment lower word
>    inc ax
>    mov 0x006c, ax
>    jnz inc_done
>    mov ax, 0x006e ; increment upper word
>    inc ax
>    mov 0x006e, ax
>
>
>
> For some reason I never see int08_handler ever been called. Any clues what may be wrong? I am creating only one VCPU
>
>
>    

Things to check:

- have you initialized the kernel PIC and PIT?
- are interrupts enabled?

-- 
error compiling committee.c: too many arguments to function

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