Update Linux to v5.4.2
Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/kernel/Kconfig.preempt b/kernel/Kconfig.preempt
index cd16551..deff972 100644
--- a/kernel/Kconfig.preempt
+++ b/kernel/Kconfig.preempt
@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0-only
choice
prompt "Preemption Model"
@@ -37,7 +38,7 @@
config PREEMPT
bool "Preemptible Kernel (Low-Latency Desktop)"
depends on !ARCH_NO_PREEMPT
- select PREEMPT_COUNT
+ select PREEMPTION
select UNINLINE_SPIN_UNLOCK if !ARCH_INLINE_SPIN_UNLOCK
help
This option reduces the latency of the kernel by making
@@ -54,7 +55,28 @@
embedded system with latency requirements in the milliseconds
range.
+config PREEMPT_RT
+ bool "Fully Preemptible Kernel (Real-Time)"
+ depends on EXPERT && ARCH_SUPPORTS_RT
+ select PREEMPTION
+ help
+ This option turns the kernel into a real-time kernel by replacing
+ various locking primitives (spinlocks, rwlocks, etc.) with
+ preemptible priority-inheritance aware variants, enforcing
+ interrupt threading and introducing mechanisms to break up long
+ non-preemptible sections. This makes the kernel, except for very
+ low level and critical code pathes (entry code, scheduler, low
+ level interrupt handling) fully preemptible and brings most
+ execution contexts under scheduler control.
+
+ Select this if you are building a kernel for systems which
+ require real-time guarantees.
+
endchoice
config PREEMPT_COUNT
- bool
\ No newline at end of file
+ bool
+
+config PREEMPTION
+ bool
+ select PREEMPT_COUNT