Hi, Please see below. vijay On 09/01/06, Rajaram Suryanarayanan <rajaram_linux@xxxxxxxxx> wrote: > Hi, > > I am confused about the mapping between devices, IRQs and the handlers. I am > following Robert Love's "Linux Kernel Development" book. > > 1. I see that different handlers can share the same IRQ with SA_SHIRQ flag. > So does it mean there can be different interrupt handlers for the same > device...? As I think each device has a unique IRQ ( strict 1-to-1 mapping > between device and its IRQ ). > No. It means that different devices can share an interrupt. All the devices need to set SA_SHIRQ flag for sharing to work. Each device will have only 1 interrupt. Each device type i.e every model has a unique dev id. Each device will have a unique IRQ (hardware interrupt). try cat /proc/interrupts. Some interrupts will be shared. > 2. Related to the first question, can different devices share the same IRQ ? > yes. If all have SA_SHIRQ enabled. If the first device does not enable sharing, no other devices can use the interrupt. > 3. Regarding dev_id parameter, is it unique to each device ? I mean is each > device has a strict 1-to-1 mapping with dev_id ? > see above > Please explain. > > Thanks, > Rajaram. > > > hope this helps. someone please correct me if anything is wrong. -vijay > > > ________________________________ > Yahoo! Photos > Got holiday prints? See all the ways to get quality prints in your hands > ASAP. > > -- Networks Lab, RPI http://poisson.ecse.rpi.edu/~vijay -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
