Merge pull request #5250 from kjbracey-arm/pbuf16

  lwIP: Add memory configs to JSON

Author: theotherjimmy

features/FEATURE_LWIP/lwip-interface/lwipopts.h

@@ -137,10 +137,25 @@
 #define LWIP_RAM_HEAP_POINTER       lwip_ram_heap
 
 // Number of pool pbufs.
-// Each requires 684 bytes of RAM.
+// Each requires 684 bytes of RAM (if MSS=536 and PBUF_POOL_BUFSIZE defaulting to be based on MSS)
+#ifdef MBED_CONF_LWIP_PBUF_POOL_SIZE
+#undef PBUF_POOL_SIZE
+#define PBUF_POOL_SIZE              MBED_CONF_LWIP_PBUF_POOL_SIZE
+#else
 #ifndef PBUF_POOL_SIZE
 #define PBUF_POOL_SIZE              5
 #endif
+#endif
+
+#ifdef MBED_CONF_LWIP_PBUF_POOL_BUFSIZE
+#undef PBUF_POOL_BUFSIZE
+#define PBUF_POOL_BUFSIZE           MBED_CONF_LWIP_PBUF_POOL_BUFSIZE
+#endif
+
+#ifdef MBED_CONF_LWIP_MEM_SIZE
+#undef MEM_SIZE
+#define MEM_SIZE                    MBED_CONF_LWIP_MEM_SIZE
+#endif
 
 // One tcp_pcb_listen is needed for each TCPServer.
 // Each requires 72 bytes of RAM.

features/FEATURE_LWIP/lwip-interface/mbed_lib.json

@@ -72,6 +72,18 @@
             "help": "Maximum number of open UDPSocket instances allowed, including one used internally for DNS.  Each requires 84 bytes of pre-allocated RAM",
             "value": 4
         },
+        "pbuf-pool-size": {
+            "help": "Number of pbufs in pool - usually used for received packets, so this determines how much data can be buffered between reception and the application reading. If a driver uses PBUF_RAM for reception, less pool may be needed. Current default (used if null here) is set to 5 in lwipopts.h, unless overridden by target Ethernet drivers.",
+            "value": null
+        },
+        "pbuf-pool-bufsize": {
+            "help": "Size of pbufs in pool. If set to null, lwIP will base the size on the TCP MSS, which is 536 unless overridden by the target",
+            "value": null
+        },
+        "mem-size": {
+            "help": "Size of heap (bytes) - used for outgoing packets, and also used by some drivers for reception. Current default (used if null here) is set to 1600 in opt.h, unless overridden by target Ethernet drivers.",
+            "value": null
+        },
         "tcpip-thread-stacksize": {
             "help": "Stack size for lwip TCPIP thread",
             "value": 1200