handling irq

[kiran mehta <kallis_john@xxxxxxxxx>]

hi , 

    I have a basic question related to interrupt
    handling.
    As we know , devices are connected to CPU's
    INT pin through PIC(programmable interrupt
    controller).whenever device interrupts , 
    PIC is notified which in turn raises CPU
    INT pin.Some number is then available on 
    data bus which is read by CPU and appropriate
    ISR is called.

    I want to know that what is this number and
    how  and who stores it in PIC memory.
    When i read irq.c and other related files
    i could not find any code which write irq number
    PIC memory.I have seen drivers which dynamically
    request for irq using request_irq function.
    Should not returned by this function 
    some how  wriiten into PIC mem.?

thanks,
      john
    




		
__________________________________ 
Do you Yahoo!? 
The all-new My Yahoo! - Get yours free! 
http://my.yahoo.com 
 


--
Kernelnewbies: Help each other learn about the Linux kernel.
Archive:       http://mail.nl.linux.org/kernelnewbies/
FAQ:           http://kernelnewbies.org/faq/