memp: allow initialization of pool memory if not in standard section

src/core/memp.c

@@ -239,6 +239,14 @@ memp_init_pool(const struct memp_desc *desc)
 
   *desc->tab = NULL;
   memp = (struct memp*)LWIP_MEM_ALIGN(desc->base);
+#if MEMP_MEM_INIT
+  /* force memset on pool memory */
+  memset(memp, 0, (size_t)desc->num * (MEMP_SIZE + desc->size
+#if MEMP_OVERFLOW_CHECK
+      + MEMP_SANITY_REGION_AFTER_ALIGNED
+#endif
+    ));
+#endif
   /* create a linked list of memp elements */
   for (i = 0; i < desc->num; ++i) {
     memp->next = *desc->tab;

src/include/lwip/opt.h

@@ -248,6 +248,15 @@
 #define MEMP_MEM_MALLOC                 0
 #endif
 
+/**
+ * MEMP_MEM_INIT==1: Force use of memset to initialize pool memory.
+ * Useful if pool are moved in uninitialized section of memory. This will ensure
+ * default values in pcbs struct are well initialized in all conditions.
+ */
+#if !defined MEMP_MEM_INIT || defined __DOXYGEN__
+#define MEMP_MEM_INIT                 0
+#endif
+
 /**
  * MEM_ALIGNMENT: should be set to the alignment of the CPU
  *    4 byte alignment -> \#define MEM_ALIGNMENT 4