Merge branch 'feature/crosscore_int' into 'master'

Add cross-core int to accelerate task being awoken from another CPU.

This adds a per-CPU interrupt that can be used to poke the CPU to go do something. In this case all that is implemented is a request to yield the current task, used in case a CPU unblocks a task that runs on another CPU. This gets rid of the limitation that inter-CPU communication using queues, muxes etc can take up to a FreeRTOS tick to happen.

Specs!
Sending an in in a queue of length 1 (essentially a semaphore) as quickly as possible (just a small delay in the sender, to make sure the receiver task gets swapped out) for 10 seconds. Number indicates the amount of ints transferred

Old code:

CPU0->CPU0: 42986

CPU0->CPU1,: 2999

New code:

CPU0->CPU0: 42868

CPU0->CPU1: 62073

See merge request !155

components/esp32/cpu_start.c

@@ -41,6 +41,7 @@
 #include "esp_event.h"
 #include "esp_spi_flash.h"
 #include "esp_ipc.h"
+#include "esp_crosscore_int.h"
 #include "esp_log.h"
 #include "esp_vfs_dev.h"
 #include "esp_newlib.h"
@@ -168,6 +169,9 @@ void start_cpu0_default(void)
     _GLOBAL_REENT->_stderr = fopen(default_uart_dev, "w");
     _GLOBAL_REENT->_stdin  = fopen(default_uart_dev, "r");
     do_global_ctors();
+#if !CONFIG_FREERTOS_UNICORE
+    esp_crosscore_int_init();
+#endif
     esp_ipc_init();
     spi_flash_init();
 
@@ -188,6 +192,7 @@ void start_cpu1_default(void)
     while (port_xSchedulerRunning[0] == 0) {
         ;
     }
+    esp_crosscore_int_init();
     ESP_LOGI(TAG, "Starting scheduler on APP CPU.");
     xPortStartScheduler();
 }

components/esp32/crosscore_int.c

@@ -0,0 +1,103 @@
+// Copyright 2015-2016 Espressif Systems (Shanghai) PTE LTD
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+#include <stdint.h>
+#include <string.h>
+
+#include "esp_attr.h"
+#include "esp_err.h"
+#include "esp_intr.h"
+
+#include "rom/ets_sys.h"
+#include "rom/uart.h"
+
+#include "soc/cpu.h"
+#include "soc/dport_reg.h"
+#include "soc/io_mux_reg.h"
+#include "soc/rtc_cntl_reg.h"
+
+#include "freertos/FreeRTOS.h"
+#include "freertos/task.h"
+#include "freertos/semphr.h"
+#include "freertos/queue.h"
+#include "freertos/portmacro.h"
+
+
+#define REASON_YIELD (1<<0)
+
+static portMUX_TYPE reasonSpinlock = portMUX_INITIALIZER_UNLOCKED;
+static volatile uint32_t reason[ portNUM_PROCESSORS ];
+
+
+/*
+ToDo: There is a small chance the CPU already has yielded when this ISR is serviced. In that case, it's running the intended task but
+the ISR will cause it to switch _away_ from it. portYIELD_FROM_ISR will probably just schedule the task again, but have to check that.
+*/
+static void esp_crosscore_isr(void *arg) {
+    uint32_t myReasonVal;
+#if 0
+    //A pointer to the correct reason array item is passed to this ISR.
+    volatile uint32_t *myReason=arg;
+#else
+    //The previous line does not work yet, the interrupt code needs work to understand two separate interrupt and argument
+    //tables... this is a valid but slightly less optimal replacement.
+    volatile uint32_t *myReason=&reason[xPortGetCoreID()];
+#endif
+    //Clear the interrupt first.
+    if (xPortGetCoreID()==0) {
+        WRITE_PERI_REG(DPORT_CPU_INTR_FROM_CPU_0_REG, 0);
+    } else {
+        WRITE_PERI_REG(DPORT_CPU_INTR_FROM_CPU_1_REG, 0);
+    }
+    //Grab the reason and clear it.
+    portENTER_CRITICAL(&reasonSpinlock);
+    myReasonVal=*myReason;
+    *myReason=0;
+    portEXIT_CRITICAL(&reasonSpinlock);
+
+    //Check what we need to do.
+    if (myReasonVal&REASON_YIELD) {
+        portYIELD_FROM_ISR();
+    }
+}
+
+//Initialize the crosscore interrupt on this core. Call this once
+//on each active core.
+void esp_crosscore_int_init() {
+    portENTER_CRITICAL(&reasonSpinlock);
+    reason[xPortGetCoreID()]=0;
+    portEXIT_CRITICAL(&reasonSpinlock);
+    ESP_INTR_DISABLE(ETS_FROM_CPU_INUM);
+    if (xPortGetCoreID()==0) {
+        intr_matrix_set(xPortGetCoreID(), ETS_FROM_CPU_INTR0_SOURCE, ETS_FROM_CPU_INUM);
+    } else {
+        intr_matrix_set(xPortGetCoreID(), ETS_FROM_CPU_INTR1_SOURCE, ETS_FROM_CPU_INUM);
+    }
+    xt_set_interrupt_handler(ETS_FROM_CPU_INUM, esp_crosscore_isr, (void*)&reason[xPortGetCoreID()]);
+    ESP_INTR_ENABLE(ETS_FROM_CPU_INUM);
+}
+
+void esp_crosscore_int_send_yield(int coreId) {
+    assert(coreId<portNUM_PROCESSORS);
+    //Mark the reason we interrupt the other CPU
+    portENTER_CRITICAL(&reasonSpinlock);
+    reason[coreId]|=REASON_YIELD;
+    portEXIT_CRITICAL(&reasonSpinlock);
+    //Poke the other CPU.
+    if (coreId==0) {
+        WRITE_PERI_REG(DPORT_CPU_INTR_FROM_CPU_0_REG, DPORT_CPU_INTR_FROM_CPU_0);
+    } else {
+        WRITE_PERI_REG(DPORT_CPU_INTR_FROM_CPU_1_REG, DPORT_CPU_INTR_FROM_CPU_1);
+    }
+}
+

components/esp32/include/esp_crosscore_int.h

@@ -0,0 +1,42 @@
+// Copyright 2015-2016 Espressif Systems (Shanghai) PTE LTD
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+#ifndef __ESP_CROSSCORE_INT_H
+#define __ESP_CROSSCORE_INT_H
+
+
+/**
+ * Initialize the crosscore interrupt system for this CPU.
+ * This needs to be called once on every CPU that is used
+ * by FreeRTOS.
+ *
+ * If multicore FreeRTOS support is enabled, this will be
+ * called automatically by the startup code and should not
+ * be called manually.
+ */
+void esp_crosscore_int_init();
+
+
+/**
+ * Send an interrupt to a CPU indicating it should yield its
+ * currently running task in favour of a higher-priority task
+ * that presumably just woke up.
+ *
+ * This is used internally by FreeRTOS in multicore mode
+ * and should not be called by the user.
+ *
+ * @param coreID Core that should do the yielding
+ */
+void esp_crosscore_int_send_yield(int coreId);
+
+#endif

components/freertos/Kconfig

@@ -133,6 +133,14 @@ menuconfig ENABLE_MEMORY_DEBUG
     help
         Enable this option to show malloc heap block and memory crash detect
 
+config FREERTOS_ISR_STACKSIZE
+    int "ISR stack size"
+    range 1536 32768
+    default 1536
+    help
+        The interrupt handlers have their own stack. The size of the stack can be defined here. 
+        Each processor has its own stack, so the total size occupied will be twice this.
+
 menuconfig FREERTOS_DEBUG_INTERNALS
     bool "Debug FreeRTOS internals"
     default n
@@ -158,6 +166,8 @@ config FREERTOS_PORTMUX_DEBUG_RECURSIVE
         If enabled, additional debug information will be printed for recursive
         portMUX usage.
 
+
+
 endif # FREERTOS_DEBUG_INTERNALS
 
 endmenu

components/freertos/include/freertos/FreeRTOSConfig.h

@@ -180,7 +180,7 @@
 /* The Xtensa port uses a separate interrupt stack. Adjust the stack size */
 /* to suit the needs of your specific application.                        */
 #ifndef configISR_STACK_SIZE
-#define configISR_STACK_SIZE			1024//2048
+#define configISR_STACK_SIZE			CONFIG_FREERTOS_ISR_STACKSIZE
 #endif
 
 /* Minimal heap size to make sure examples can run on memory limited

components/freertos/include/freertos/portable.h

@@ -179,6 +179,14 @@ BaseType_t xPortStartScheduler( void ) PRIVILEGED_FUNCTION;
  */
 void vPortEndScheduler( void ) PRIVILEGED_FUNCTION;
 
+
+/*
+ * Send an interrupt to another core in order to make the task running
+ * on it yield for a higher-priority task.
+ */
+
+void vPortYieldOtherCore( BaseType_t coreid) PRIVILEGED_FUNCTION;
+
 /*
  * The structures and methods of manipulating the MPU are contained within the
  * port layer.

components/freertos/port.c

@@ -103,6 +103,8 @@
 
 #include "esp_panic.h"
 
+#include "esp_crosscore_int.h"
+
 /* Defined in portasm.h */
 extern void _frxt_tick_timer_init(void);
 
@@ -228,6 +230,12 @@ BaseType_t xPortSysTickHandler( void )
 
 	return ret;
 }
+
+
+void vPortYieldOtherCore( BaseType_t coreid ) {
+	esp_crosscore_int_send_yield( coreid );
+}
+
 /*-----------------------------------------------------------*/
 
 /*

components/freertos/tasks.c

@@ -261,7 +261,7 @@ PRIVILEGED_DATA static List_t xDelayedTaskList1;						/*< Delayed tasks. */
 PRIVILEGED_DATA static List_t xDelayedTaskList2;						/*< Delayed tasks (two lists are used - one for delays that have overflowed the current tick count. */
 PRIVILEGED_DATA static List_t * volatile pxDelayedTaskList;				/*< Points to the delayed task list currently being used. */
 PRIVILEGED_DATA static List_t * volatile pxOverflowDelayedTaskList;		/*< Points to the delayed task list currently being used to hold tasks that have overflowed the current tick count. */
-PRIVILEGED_DATA static List_t xPendingReadyList;						/*< Tasks that have been readied while the scheduler was suspended.  They will be moved to the ready list when the scheduler is resumed. */
+PRIVILEGED_DATA static List_t xPendingReadyList[ portNUM_PROCESSORS ];						/*< Tasks that have been readied while the scheduler was suspended.  They will be moved to the ready list when the scheduler is resumed. */
 
 #if ( INCLUDE_vTaskDelete == 1 )
 
@@ -288,7 +288,7 @@ PRIVILEGED_DATA static volatile TickType_t xTickCount 				= ( TickType_t ) 0U;
 PRIVILEGED_DATA static volatile UBaseType_t uxTopReadyPriority 		= tskIDLE_PRIORITY;
 PRIVILEGED_DATA static volatile BaseType_t xSchedulerRunning 		= pdFALSE;
 PRIVILEGED_DATA static volatile UBaseType_t uxPendedTicks 			= ( UBaseType_t ) 0U;
-PRIVILEGED_DATA static volatile BaseType_t xYieldPending 			= pdFALSE;
+PRIVILEGED_DATA static volatile BaseType_t xYieldPending[portNUM_PROCESSORS] 		= {pdFALSE};
 PRIVILEGED_DATA static volatile BaseType_t xNumOfOverflows 			= ( BaseType_t ) 0;
 PRIVILEGED_DATA static UBaseType_t uxTaskNumber 					= ( UBaseType_t ) 0U;
 PRIVILEGED_DATA static volatile TickType_t xNextTaskUnblockTime		= portMAX_DELAY;
@@ -442,6 +442,9 @@ count overflows. */
 	vListInsertEnd( &( pxReadyTasksLists[ ( pxTCB )->uxPriority ] ), &( ( pxTCB )->xGenericListItem ) )
 /*-----------------------------------------------------------*/
 
+
+#define tskCAN_RUN_HERE( cpuid ) ( cpuid==xPortGetCoreID() || cpuid==tskNO_AFFINITY )
+
 /*
  * Several functions take an TaskHandle_t parameter that can optionally be NULL,
  * where NULL is used to indicate that the handle of the currently executing
@@ -614,6 +617,34 @@ static void prvAddNewTaskToReadyList( TCB_t *pxNewTCB, TaskFunction_t pxTaskCode
 
 /*-----------------------------------------------------------*/
 
+/*
+ * This routine tries to send an interrupt to another core if needed to make it execute a task
+ * of higher priority. We try to figure out if needed first by inspecting the pxTCB of the 
+ * other CPU first. Specifically for Xtensa, we can do this because pxTCB is an atomic pointer. It
+ * is possible that it is inaccurate because the other CPU just did a task switch, but in that case
+ * at most a superfluous interrupt is generated.
+*/
+void taskYIELD_OTHER_CORE( BaseType_t xCoreID, UBaseType_t uxPriority )
+{
+	BaseType_t i;
+	if (xCoreID != tskNO_AFFINITY) {
+		if ( pxCurrentTCB[ xCoreID ]->uxPriority < uxPriority ) {
+			vPortYieldOtherCore( xCoreID );
+		}
+	}
+	else
+	{
+		/* The task has no affinity. See if we can find a CPU to put it on.*/
+		for (i=0; i<portNUM_PROCESSORS; i++) {
+			if (i != xPortGetCoreID() && pxCurrentTCB[ i ]->uxPriority < uxPriority)
+			{
+				vPortYieldOtherCore( i );
+				break;
+			}
+		}
+	}
+}
+
 #if( configSUPPORT_STATIC_ALLOCATION == 1 )
 
 	TaskHandle_t xTaskCreateStaticPinnedToCore(	TaskFunction_t pxTaskCode,
@@ -1087,7 +1118,21 @@ static void prvAddNewTaskToReadyList( TCB_t *pxNewTCB, TaskFunction_t pxTaskCode
 		//No mux here, uxPriority is mostly atomic and there's not really any harm if this check misfires.
 		if( pxCurrentTCB[ xPortGetCoreID() ]->uxPriority < pxNewTCB->uxPriority )
 		{
-			taskYIELD_IF_USING_PREEMPTION();
+			/* Scheduler is running. If the created task is of a higher priority than an executing task
+			  then it should run now.
+			  No mux here, uxPriority is mostly atomic and there's not really any harm if this check misfires.
+			*/
+			if( tskCAN_RUN_HERE( xCoreID ) && pxCurrentTCB[ xPortGetCoreID() ]->uxPriority < pxNewTCB->uxPriority )
+			{
+				taskYIELD_IF_USING_PREEMPTION();
+			}
+			else if( xCoreID != xPortGetCoreID() ) {
+				taskYIELD_OTHER_CORE(xCoreID, pxNewTCB->uxPriority);
+			}
+			else
+			{
+				mtCOVERAGE_TEST_MARKER();
+			}
 		}
 		else
 		{
@@ -1163,7 +1208,7 @@ static void prvAddNewTaskToReadyList( TCB_t *pxNewTCB, TaskFunction_t pxTaskCode
 				after which it is not possible to yield away from this task -
 				hence xYieldPending is used to latch that a context switch is
 				required. */
-				portPRE_TASK_DELETE_HOOK( pxTCB, &xYieldPending );
+				portPRE_TASK_DELETE_HOOK( pxTCB, &xYieldPending[xPortGetCoreID()] );
 				portYIELD_WITHIN_API();
 			}
 			else
@@ -1517,10 +1562,14 @@ static void prvAddNewTaskToReadyList( TCB_t *pxNewTCB, TaskFunction_t pxTaskCode
 						/* The priority of a task other than the currently
 						running task is being raised.  Is the priority being
 						raised above that of the running task? */
-						if( uxNewPriority >= pxCurrentTCB[ xPortGetCoreID() ]->uxPriority )
+						if ( tskCAN_RUN_HERE(pxTCB->xCoreID) && uxNewPriority >= pxCurrentTCB[ xPortGetCoreID() ]->uxPriority )
 						{
 							xYieldRequired = pdTRUE;
 						}
+						else if ( pxTCB->xCoreID != xPortGetCoreID() ) 
+						{
+							taskYIELD_OTHER_CORE( pxTCB->xCoreID, uxNewPriority );
+						}
 						else
 						{
 							mtCOVERAGE_TEST_MARKER();
@@ -1742,7 +1791,7 @@ static void prvAddNewTaskToReadyList( TCB_t *pxNewTCB, TaskFunction_t pxTaskCode
 		if( listIS_CONTAINED_WITHIN( &xSuspendedTaskList, &( pxTCB->xGenericListItem ) ) != pdFALSE )
 		{
 			/* Has the task already been resumed from within an ISR? */
-			if( listIS_CONTAINED_WITHIN( &xPendingReadyList, &( pxTCB->xEventListItem ) ) == pdFALSE )
+			if( listIS_CONTAINED_WITHIN( &xPendingReadyList[ xPortGetCoreID() ], &( pxTCB->xEventListItem ) ) == pdFALSE )
 			{
 				/* Is it in the suspended list because it is in the	Suspended
 				state, or because is is blocked with no timeout? */
@@ -1799,13 +1848,17 @@ static void prvAddNewTaskToReadyList( TCB_t *pxNewTCB, TaskFunction_t pxTaskCode
 					prvAddTaskToReadyList( pxTCB );
 
 					/* We may have just resumed a higher priority task. */
-					if( pxTCB->uxPriority >= pxCurrentTCB[ xPortGetCoreID() ]->uxPriority )
+					if( tskCAN_RUN_HERE(pxTCB->xCoreID) && pxTCB->uxPriority >= pxCurrentTCB[ xPortGetCoreID() ]->uxPriority )
 					{
 						/* This yield may not cause the task just resumed to run,
 						but will leave the lists in the correct state for the
 						next yield. */
 						taskYIELD_IF_USING_PREEMPTION_MUX(&xTaskQueueMutex);
 					}
+					else if( pxTCB->xCoreID != xPortGetCoreID() )
+					{
+						taskYIELD_OTHER_CORE( pxTCB->xCoreID, pxTCB->uxPriority );
+					}
 					else
 					{
 						mtCOVERAGE_TEST_MARKER();
@@ -1830,7 +1883,6 @@ static void prvAddNewTaskToReadyList( TCB_t *pxNewTCB, TaskFunction_t pxTaskCode
 
 #if ( ( INCLUDE_xTaskResumeFromISR == 1 ) && ( INCLUDE_vTaskSuspend == 1 ) )
 
-/* ToDo: Make this multicore-compatible. */
 	BaseType_t xTaskResumeFromISR( TaskHandle_t xTaskToResume )
 	{
 	BaseType_t xYieldRequired = pdFALSE;
@@ -1850,24 +1902,28 @@ static void prvAddNewTaskToReadyList( TCB_t *pxNewTCB, TaskFunction_t pxTaskCode
 				{
 					/* Ready lists can be accessed so move the task from the
 					suspended list to the ready list directly. */
-					if( pxTCB->uxPriority >= pxCurrentTCB[ xPortGetCoreID() ]->uxPriority )
+					( void ) uxListRemove(  &( pxTCB->xGenericListItem ) );
+					prvAddTaskToReadyList( pxTCB );
+
+					if( tskCAN_RUN_HERE( pxTCB->xCoreID ) && pxTCB->uxPriority >= pxCurrentTCB[ xPortGetCoreID() ]->uxPriority )
 					{
 						xYieldRequired = pdTRUE;
 					}
+					else if ( pxTCB->xCoreID != xPortGetCoreID() )
+					{
+						taskYIELD_OTHER_CORE( pxTCB->xCoreID, pxTCB->uxPriority);
+					}
 					else
 					{
 						mtCOVERAGE_TEST_MARKER();
 					}
-
-					( void ) uxListRemove(  &( pxTCB->xGenericListItem ) );
-					prvAddTaskToReadyList( pxTCB );
 				}
 				else
 				{
 					/* The delayed or ready lists cannot be accessed so the task
 					is held in the pending ready list until the scheduler is
 					unsuspended. */
-					vListInsertEnd( &( xPendingReadyList ), &( pxTCB->xEventListItem ) );
+					vListInsertEnd( &( xPendingReadyList[ xPortGetCoreID() ] ), &( pxTCB->xEventListItem ) );
 				}
 			}
 			else
@@ -2052,18 +2108,19 @@ BaseType_t xAlreadyYielded = pdFALSE;
 			{
 				/* Move any readied tasks from the pending list into the
 				appropriate ready list. */
-				while( listLIST_IS_EMPTY( &xPendingReadyList ) == pdFALSE )
+				while( listLIST_IS_EMPTY( &xPendingReadyList[ xPortGetCoreID() ] ) == pdFALSE )
 				{
-					pxTCB = ( TCB_t * ) listGET_OWNER_OF_HEAD_ENTRY( ( &xPendingReadyList ) );
+					pxTCB = ( TCB_t * ) listGET_OWNER_OF_HEAD_ENTRY( ( &xPendingReadyList[ xPortGetCoreID() ] ) );
 					( void ) uxListRemove( &( pxTCB->xEventListItem ) );
 					( void ) uxListRemove( &( pxTCB->xGenericListItem ) );
 					prvAddTaskToReadyList( pxTCB );
 
 					/* If the moved task has a priority higher than the current
 					task then a yield must be performed. */
-					if( pxTCB->uxPriority >= pxCurrentTCB[ xPortGetCoreID() ]->uxPriority )
+					if ( tskCAN_RUN_HERE(pxTCB->xCoreID) && pxTCB->uxPriority >= pxCurrentTCB[ xPortGetCoreID() ]->uxPriority )
 					{
-						xYieldPending = pdTRUE;
+						/* We can schedule the awoken task on this CPU. */
+						xYieldPending[xPortGetCoreID()] = pdTRUE;
 						break;
 					}
 					else
@@ -2082,7 +2139,7 @@ BaseType_t xAlreadyYielded = pdFALSE;
 					{
 						if( xTaskIncrementTick() != pdFALSE )
 						{
-							xYieldPending = pdTRUE;
+							xYieldPending[ xPortGetCoreID() ] = pdTRUE;
 						}
 						else
 						{
@@ -2096,7 +2153,7 @@ BaseType_t xAlreadyYielded = pdFALSE;
 					mtCOVERAGE_TEST_MARKER();
 				}
 
-				if( xYieldPending == pdTRUE )
+				if( xYieldPending[ xPortGetCoreID() ] == pdTRUE )
 				{
 					#if( configUSE_PREEMPTION != 0 )
 					{
@@ -2480,7 +2537,7 @@ BaseType_t xSwitchRequired = pdFALSE;
 
 	#if ( configUSE_PREEMPTION == 1 )
 	{
-		if( xYieldPending != pdFALSE )
+		if( xYieldPending [ xPortGetCoreID() ] != pdFALSE )
 		{
 			xSwitchRequired = pdTRUE;
 		}
@@ -2596,11 +2653,11 @@ void vTaskSwitchContext( void )
 	{
 		/* The scheduler is currently suspended - do not allow a context
 		switch. */
-		xYieldPending = pdTRUE;
+		xYieldPending[ xPortGetCoreID() ] = pdTRUE;
 	}
 	else
 	{
-		xYieldPending = pdFALSE;
+		xYieldPending[ xPortGetCoreID() ] = pdFALSE;
 		traceTASK_SWITCHED_OUT();
 
 		#if ( configGENERATE_RUN_TIME_STATS == 1 )
@@ -2951,11 +3008,11 @@ BaseType_t xReturn;
 		/* The delayed and ready lists cannot be accessed, so hold this task
 		pending until the scheduler is resumed. */
 		taskENTER_CRITICAL(&xTaskQueueMutex);
-		vListInsertEnd( &( xPendingReadyList ), &( pxUnblockedTCB->xEventListItem ) );
+		vListInsertEnd( &( xPendingReadyList[ xPortGetCoreID() ] ), &( pxUnblockedTCB->xEventListItem ) );
 		taskEXIT_CRITICAL(&xTaskQueueMutex);
 	}
 
-	if( pxUnblockedTCB->uxPriority > pxCurrentTCB[ xPortGetCoreID() ]->uxPriority )
+	if ( tskCAN_RUN_HERE(pxUnblockedTCB->xCoreID) && pxUnblockedTCB->uxPriority >= pxCurrentTCB[ xPortGetCoreID() ]->uxPriority )
 	{
 		/* Return true if the task removed from the event list has a higher
 		priority than the calling task.  This allows the calling task to know if
@@ -2964,7 +3021,12 @@ BaseType_t xReturn;
 
 		/* Mark that a yield is pending in case the user is not using the
 		"xHigherPriorityTaskWoken" parameter to an ISR safe FreeRTOS function. */
-		xYieldPending = pdTRUE;
+		xYieldPending[ xPortGetCoreID() ] = pdTRUE;
+	}
+	else if ( pxUnblockedTCB->xCoreID != xPortGetCoreID() )
+	{
+		taskYIELD_OTHER_CORE( pxUnblockedTCB->xCoreID, pxUnblockedTCB->uxPriority );
+		xReturn = pdFALSE;
 	}
 	else
 	{
@@ -3015,7 +3077,7 @@ BaseType_t xReturn;
 	( void ) uxListRemove( &( pxUnblockedTCB->xGenericListItem ) );
 	prvAddTaskToReadyList( pxUnblockedTCB );
 
-	if( pxUnblockedTCB->uxPriority > pxCurrentTCB[ xPortGetCoreID() ]->uxPriority )
+	if ( tskCAN_RUN_HERE(pxUnblockedTCB->xCoreID) && pxUnblockedTCB->uxPriority >= pxCurrentTCB[ xPortGetCoreID() ]->uxPriority )
 	{
 		/* Return true if the task removed from the event list has
 		a higher priority than the calling task.  This allows
@@ -3025,7 +3087,12 @@ BaseType_t xReturn;
 
 		/* Mark that a yield is pending in case the user is not using the
 		"xHigherPriorityTaskWoken" parameter to an ISR safe FreeRTOS function. */
-		xYieldPending = pdTRUE;
+		xYieldPending[ xPortGetCoreID() ] = pdTRUE;
+	}
+	else if ( pxUnblockedTCB->xCoreID != xPortGetCoreID() )
+	{
+		taskYIELD_OTHER_CORE( pxUnblockedTCB->xCoreID, pxUnblockedTCB->uxPriority );
+		xReturn = pdFALSE;
 	}
 	else
 	{
@@ -3096,7 +3163,7 @@ BaseType_t xReturn;
 
 void vTaskMissedYield( void )
 {
-	xYieldPending = pdTRUE;
+	xYieldPending[ xPortGetCoreID() ] = pdTRUE;
 }
 /*-----------------------------------------------------------*/
 
@@ -3261,12 +3328,12 @@ static portTASK_FUNCTION( prvIdleTask, pvParameters )
 	eSleepModeStatus eReturn = eStandardSleep;
 		taskENTER_CRITICAL(&xTaskQueueMutex);
 
-		if( listCURRENT_LIST_LENGTH( &xPendingReadyList ) != 0 )
+		if( listCURRENT_LIST_LENGTH( &xPendingReadyList[ xPortGetCoreID() ] ) != 0 )
 		{
 			/* A task was made ready while the scheduler was suspended. */
 			eReturn = eAbortSleep;
 		}
-		else if( xYieldPending != pdFALSE )
+		else if( xYieldPending[ xPortGetCoreID() ] != pdFALSE )
 		{
 			/* A yield was pended while the scheduler was suspended. */
 			eReturn = eAbortSleep;
@@ -3390,7 +3457,7 @@ UBaseType_t uxPriority;
 
 	vListInitialise( &xDelayedTaskList1 );
 	vListInitialise( &xDelayedTaskList2 );
-	vListInitialise( &xPendingReadyList );
+	vListInitialise( &xPendingReadyList[ xPortGetCoreID() ] );
 
 	#if ( INCLUDE_vTaskDelete == 1 )
 	{
@@ -3781,12 +3848,6 @@ TCB_t *pxTCB;
 #endif /* ( ( INCLUDE_xTaskGetSchedulerState == 1 ) || ( configUSE_TIMERS == 1 ) ) */
 /*-----------------------------------------------------------*/
 
-/*
-ToDo: Mutexes haven't been tested or adapted to multicore at all.
-
-In fact, nothing below this line has/is.
-*/
-
 #if ( configUSE_MUTEXES == 1 )
 
 	void vTaskPriorityInherit( TaskHandle_t const pxMutexHolder )
@@ -4624,12 +4685,16 @@ TickType_t uxReturn;
 				/* The task should not have been on an event list. */
 				configASSERT( listLIST_ITEM_CONTAINER( &( pxTCB->xEventListItem ) ) == NULL );
 
-				if( pxTCB->uxPriority > pxCurrentTCB[ xPortGetCoreID() ]->uxPriority )
+				if( tskCAN_RUN_HERE(pxTCB->xCoreID) && pxTCB->uxPriority > pxCurrentTCB[ xPortGetCoreID() ]->uxPriority )
 				{
 					/* The notified task has a priority above the currently
 					executing task so a yield is required. */
 					portYIELD_WITHIN_API();
 				}
+				else if ( pxTCB->xCoreID != xPortGetCoreID() )
+				{
+					taskYIELD_OTHER_CORE(pxTCB->xCoreID, pxTCB->uxPriority);
+				}
 				else
 				{
 					mtCOVERAGE_TEST_MARKER();
@@ -4717,10 +4782,10 @@ TickType_t uxReturn;
 				{
 					/* The delayed and ready lists cannot be accessed, so hold
 					this task pending until the scheduler is resumed. */
-					vListInsertEnd( &( xPendingReadyList ), &( pxTCB->xEventListItem ) );
+					vListInsertEnd( &( xPendingReadyList[ xPortGetCoreID() ] ), &( pxTCB->xEventListItem ) );
 				}
 
-				if( pxTCB->uxPriority > pxCurrentTCB[ xPortGetCoreID() ]->uxPriority )
+				if( tskCAN_RUN_HERE(pxTCB->xCoreID) && pxTCB->uxPriority > pxCurrentTCB[ xPortGetCoreID() ]->uxPriority )
 				{
 					/* The notified task has a priority above the currently
 					executing task so a yield is required. */
@@ -4729,6 +4794,10 @@ TickType_t uxReturn;
 						*pxHigherPriorityTaskWoken = pdTRUE;
 					}
 				}
+				else if ( pxTCB->xCoreID != xPortGetCoreID() )
+				{
+					taskYIELD_OTHER_CORE( pxTCB->xCoreID, pxTCB->uxPriority );
+				}
 				else
 				{
 					mtCOVERAGE_TEST_MARKER();
@@ -4781,10 +4850,10 @@ TickType_t uxReturn;
 				{
 					/* The delayed and ready lists cannot be accessed, so hold
 					this task pending until the scheduler is resumed. */
-					vListInsertEnd( &( xPendingReadyList ), &( pxTCB->xEventListItem ) );
+					vListInsertEnd( &( xPendingReadyList[ xPortGetCoreID() ] ), &( pxTCB->xEventListItem ) );
 				}
-
-				if( pxTCB->uxPriority > pxCurrentTCB[ xPortGetCoreID() ]->uxPriority )
+				
+				if( tskCAN_RUN_HERE(pxTCB->xCoreID) && pxTCB->uxPriority > pxCurrentTCB[ xPortGetCoreID() ]->uxPriority )
 				{
 					/* The notified task has a priority above the currently
 					executing task so a yield is required. */
@@ -4793,6 +4862,10 @@ TickType_t uxReturn;
 						*pxHigherPriorityTaskWoken = pdTRUE;
 					}
 				}
+				else if ( pxTCB->xCoreID != xPortGetCoreID() )
+				{
+					taskYIELD_OTHER_CORE( pxTCB->xCoreID, pxTCB->uxPriority );
+				}
 				else
 				{
 					mtCOVERAGE_TEST_MARKER();