Hi Arun, On Wed, Apr 18, 2012 at 1:08 AM, Arun KS <getarunks@xxxxxxxxx> wrote: > Hi Dave, > > Thanks for your reply. > > On Wed, Apr 18, 2012 at 1:01 PM, Dave Hylands <dhylands@xxxxxxxxx> wrote: >> >> Hi Arun, >> >> On Tue, Apr 17, 2012 at 11:44 PM, Arun KS <getarunks@xxxxxxxxx> wrote: >> > >> > Hello Guys, >> > >> > System is working normal after this BUG. >> > PC is at 0x400b4614, probably a mmaped address. >> > >> > Just wondering how can this BUG happen when a process is running in user >> > space. >> > >> > Can it be something like this >> > 1) enter to kernel from userspace through some system call. >> > 2) kernel disables the interrupt and return to user space. >> >> Don't do that > > > I don't do that. This scenario mentioned is a just a wild guess. >> >> >> > 3) and now it can happen in user space? >> >> Because something in userspace made a blocking call which would cause >> a context switch to occur and your driver erroneously left interrupts >> disabled. > > In that case, my system should have been unstable afterwards if interrupts > are left disabled. But that is not happening. > > If we return to user space with interrupts disabled, can we switch back > again to kernel using a system cal(because interrupts are already disabled)? As long as you don't do anything which would need to block. A buggy driver could also interrupt user-code (hardware interrupt) and disable interrupts and not re-enable them. -- Dave Hylands Shuswap, BC, Canada http://www.davehylands.com _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
