Hi Guys, I have a question related to task switching.Basically when user space application switches to kernel (through sys calls), which stack will be used for the user app.Mainly I want to know how the current pointer implementation works. I saw that in arm they are masking the sp with ~(THREAD_SIZE -1) and getting the current thread info and from there its taking the task pointer. So here I am a little confused about the stack pointer since when it switches the kernel it will be supervisory mode,so which sp it's referencing.I know it will be a supervisory stack,but how this stack will be related with the user app. If anybody could give a pointer on this,it would be of great help to me. -- With Regards Subin Gangadharan I am not afraid and I am also not afraid of being afraid.