Prerequisites
Generic requirements
The interrupt pipeline requires the following features to be available from the target Linux kernel:
-
Generic IRQ handling (CONFIG_GENERIC_IRQ) and IRQ domains (CONFIG_IRQ_DOMAIN), which most architectures should support these days.
-
Generic clock event abstraction (CONFIG_GENERIC_CLOCKEVENTS).
-
Generic clock source abstraction (!CONFIG_ARCH_USES_GETTIMEOFFSET).
Other assumptions
ARM
-
a target ARM machine port must be allowed to specify its own IRQ handler at run time (CONFIG_MULTI_IRQ_HANDLER).
-
only armv6 CPUs and later are supported, excluding older generations of ARM CPUs. Support for ASID (CONFIG_CPU_HAS_ASID) is required.
-
machine does not have VIVT cache.
armv5 is not supported due to the use of VIVT caches on these CPUs, which don’t cope well - at all - with low latency requirements. A work aimed at leveraging the legacy FCSE PID register for reducing the cost of cache invalidation in context switches has been maintained until 2013 by Gilles Chanteperdrix, as part of the legacy I-pipe project, a Dovetail ancestor. This work can still be cloned from this GIT repository.
