hi I am working on powerpc(Mpc860T) with linux-2.4 kernnel, As I am developping application using spi and with irqs: For each one millisec I am getting siu interrupt,In the interrupt handler I have to load frequency(using spi communication) I am able to write it (I am able load the frequency also) All other interrupts I am using are cpm interrupts(smc2.timer2,spi),one siu interrupt for the present , I am facing the following problems: 1.system rebooting: case-if i tried to write continuously to externel hardware through spi ,in externel (siu)intrrupt handler,and timer2(cpm)intrrupt handler, 2. if I limited number of times of write to hardware system not getting rebooted. I observed that the problem occured due to passing of control signals to externel hardware (those are memory mapped signals) in irqs.how can i solve this with getting rebooted. thanks to all ... Bharathi --------------------------------- Sponsored Link Degrees online in as fast as 1 Yr - MBA, Bachelor's, Master's, Associate - Click now to apply