CONFIG_SWP_EMULATION is not available for thedefaultarchitecture x86.
Result is shown for architecture arm64
Emulate SWP/SWPB instructions
configname: CONFIG_SWP_EMULATION
Linux Kernel Configuration
└─>Kernel Features
└─>Kernel support for 32-bit EL0
└─>Emulate deprecated/obsolete ARMv8 instructions
└─>Emulate SWP/SWPB instructions
In linux kernel since version 3.10 (release Date: 2013-06-30)
ARMv8 obsoletes the use of A32 SWP/SWPB instructions such that
they are always undefined. Say Y here to enable software
emulation of these instructions for userspace using LDXR/STXR.
This feature can be controlled at runtime with the abi.swp
sysctl which is disabled by default.
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, LDXR/STXR 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
they are always undefined. Say Y here to enable software
emulation of these instructions for userspace using LDXR/STXR.
This feature can be controlled at runtime with the abi.swp
sysctl which is disabled by default.
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, LDXR/STXR 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