Add support to OpenOCD FreeRTOS debug

FreeRTOS/CMakeLists.txt

@@ -32,6 +32,7 @@ set(LIBFREERTOS_SRCS ${LIBFREERTOS_SRCS}
   timers.c
   tasks.c
   event_groups.c
+  openocd.c
   )
 
 include_directories(${UCONTROLLER_HDRS})

FreeRTOS/openocd.c

@@ -0,0 +1,20 @@
+/*
+ * Since at least FreeRTOS V7.5.3 uxTopUsedPriority is no longer
+ * present in the kernel, so it has to be supplied by other means for
+ * OpenOCD's threads awareness.
+ *
+ * Add this file to your project, and, if you're using --gc-sections,
+ * ``--undefined=uxTopUsedPriority'' (or
+ * ``-Wl,--undefined=uxTopUsedPriority'' when using gcc for final
+ * linking) to your LDFLAGS; same with all the other symbols you need.
+ */
+
+#include "FreeRTOS.h"
+
+#ifdef __GNUC__
+#define USED __attribute__((used))
+#else
+#define USED
+#endif
+
+volatile const int USED uxTopUsedPriority = configMAX_PRIORITIES - 1;

toolchain/toolchain-arm-none-eabi.cmake

@@ -29,4 +29,4 @@ set( CMAKE_OBJDUMP ${TC_PATH}${CROSS_COMPILE}objdump
 set(COMMON_FLAGS "-fno-common -fno-builtin -ffunction-sections -fdata-sections -fno-strict-aliasing -fmessage-length=0")
 set(CMAKE_C_FLAGS "${COMMON_FLAGS} -std=gnu99")
 set(CMAKE_CXX_FLAGS "${COMMON_FLAGS} -std=gnu++0x")
-set(CMAKE_EXE_LINKER_FLAGS "-Wl,-gc-sections --specs=nosys.specs -nostdlib -static -nostartfiles")
+set(CMAKE_EXE_LINKER_FLAGS "-Wl,--gc-sections,--undefined=uxTopUsedPriority --specs=nosys.specs -nostdlib -static -nostartfiles")