Philippe Gerum authored Dec 05, 2020 and Jan Kiszka committed Dec 14, 2020

Allowing the task context switching code to be preempted by local
interrupts was an optimization targeted at low-end ARM armv4/5 cores
with sluggish VIVT caches, at the expense of significant complexity in
the IRQ pipeline and Cobalt scheduler. Support for armv4/5 is long
gone for Xenomai, and maintaining such feature is not worth the burden
with the VIPT caches exhibited by current micro-architectures such as
armv7.

Dovetail provides some form of preemptible context switching of
in-band tasks specifically, which requires no support from Cobalt.

So we may disable this Cobalt-specific feature entirely for ARM.

Signed-off-by: Philippe Gerum <rpm@xenomai.org>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>