Update SMP branch readme for port migration (#999)
diff --git a/README.md b/README.md
index 067f6a0..ef2c293 100644
--- a/README.md
+++ b/README.md
@@ -9,6 +9,44 @@
Have more questions? Post them in the [FreeRTOS forum](https://forums.freertos.org/).
+## Migrate port from SMP branch to FreeRTOS v11
+
+The following changes should be applied to migrate a port from this branch to FreeRTOS v11:
+
+* Call `xTaskIncrementTick` in critical section in port
+
+RP2040 example:
+```c
+void xPortSysTickHandler( void )
+{
+ portBASE_TYPE xPreviousMask;
+
+ /* xTaskIncrementTick now must be called in critical section. */
+ xPreviousMask = taskENTER_CRITICAL_FROM_ISR();
+ {
+ /* Increment the RTOS tick. */
+ if( xTaskIncrementTick() != pdFALSE )
+ {
+ /* Pend a context switch. */
+ portNVIC_INT_CTRL_REG = portNVIC_PENDSVSET_BIT;
+ }
+ }
+ taskEXIT_CRITICAL_FROM_ISR( xPreviousMask );
+}
+```
+
+* Rename `configNUM_CORES` to `configNUMBER_OF_CORES`
+
+* Define `portSET/CLEAR_INTERRUPT_MASK` in port
+
+* Define `portENTER/EXIT_CRITICAL_FROM_ISR` for SMP in port
+ * These macros should be implemented with `vTaskEnterCriticalFromISR`/`xTaskExitCriticalFromISR`
+
+* Update `portSET/CLEAR_INTERRUPT_MASK_FROM_ISR` implementation in port
+ * SMP-dev doesnt use these macros to enter/exit critical section from ISR. Instead,
+ `portENTER/EXIT_CRITICAL_FROM_ISR` are used. These functions should be implemented as
+ the macro name suggested, set or clear interrupt mask from ISR if nested interrupt are supported.
+
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