kernel: add kconfig CONFIG_KERNEL_MEM_POOL

Adds a kconfig CONFIG_KERNEL_MEM_POOL to decide whether
kernel memory pool related code is compiled. This option
can be disabled to shrink code size. If k_heap is not
being used at all, kheap.c will also not be compiled,
resulting in further smaller code size.

Signed-off-by: Daniel Leung <daniel.leung@intel.com>

kernel/CMakeLists.txt

@@ -11,7 +11,6 @@ add_library(kernel
   kheap.c
   mailbox.c
   mem_slab.c
-  mempool.c
   msg_q.c
   mutex.c
   pipes.c
@@ -42,9 +41,13 @@ target_sources_ifdef(CONFIG_ATOMIC_OPERATIONS_C   kernel PRIVATE atomic_c.c)
 target_sources_ifdef(CONFIG_MMU                   kernel PRIVATE mmu.c)
 target_sources_ifdef(CONFIG_POLL                  kernel PRIVATE poll.c)
 
-if(${CONFIG_MEM_POOL_HEAP_BACKEND})
-else()
-  target_sources(kernel PRIVATE mempool_sys.c)
+if(${CONFIG_KERNEL_MEM_POOL})
+  target_sources(kernel PRIVATE mempool.c)
+
+  if(${CONFIG_MEM_POOL_HEAP_BACKEND})
+  else()
+    target_sources(kernel PRIVATE mempool_sys.c)
+  endif()
 endif()
 
 # The last 2 files inside the target_sources_ifdef should be

kernel/Kconfig

@@ -444,6 +444,16 @@ config NUM_PIPE_ASYNC_MSGS
 	  Setting this option to 0 disables support for asynchronous
 	  pipe messages.
 
+config KERNEL_MEM_POOL
+	bool "Use Kernel Memory Pool"
+	default y
+	help
+	  Enable the use of kernel memory pool.
+
+	  Say y if unsure.
+
+if KERNEL_MEM_POOL
+
 config MEM_POOL_HEAP_BACKEND
 	bool "Use k_heap as the backend for k_mem_pool"
 	default y
@@ -472,6 +482,9 @@ config HEAP_MEM_POOL_MIN_SIZE
 	  This option specifies the size of the smallest block in the pool.
 	  Option must be a power of 2 and lower than or equal to the size
 	  of the entire pool.
+
+endif # KERNEL_MEM_POOL
+
 endmenu
 
 config ARCH_HAS_CUSTOM_SWAP_TO_MAIN