1 files changed, 35 insertions, 0 deletions

diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig
index 4414a01e1e8a..8493ed04797a 100644
--- a/arch/arm/mm/Kconfig
+++ b/arch/arm/mm/Kconfig
@@ -599,6 +599,14 @@ config CPU_CP15_MPU
         help
           Processor has the CP15 register, which has MPU related registers.
 
+config CPU_USE_DOMAINS
+        bool
+        depends on MMU
+        default y if !CPU_32v6K
+        help
+          This option enables or disables the use of domain switching
+          via the set_fs() function.
+
 #
 # CPU supports 36-bit I/O
 #
@@ -628,6 +636,33 @@ config ARM_THUMBEE
           Say Y here if you have a CPU with the ThumbEE extension and code to
           make use of it. Say N for code that can run on CPUs without ThumbEE.
 
+config SWP_EMULATE
+        bool "Emulate SWP/SWPB instructions"
+        depends on CPU_V7
+        select HAVE_PROC_CPU if PROC_FS
+        default y if SMP
+        help
+          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.
+
 config CPU_BIG_ENDIAN
         bool "Build big-endian kernel"
         depends on ARCH_SUPPORTS_BIG_ENDIAN