ARMv6 architecture deprecates use of the SWP/SWPB instructions.
ARMv7 multiprocessing extensions introduce the ability to disable
these instructions, triggering an undefined instruction exception
when executed. Say Y here to enable software emulation of these
instructions for userspace (not kernel) using LDREX/STREX.
Also creates /proc/cpu/swp_emulation for statistics.

In some older versions of glibc [<=2.8] SWP is used during futex
trylock() operations with the assumption that the code will not
be preempted. This invalid assumption may be more likely to fail
with SWP emulation enabled, leading to deadlock of the user
application.

NOTE: when accessing uncached shared regions, LDREX/STREX rely
on an external transaction monitoring block called a global
monitor to maintain update atomicity. If your system does not
implement a global monitor, this option can cause programs that
perform SWP operations to uncached memory to deadlock.

If unsure, say Y.

source code:

arch/arm/kernel/swp_emulate.c