gnrc/pktbuf : Expose to Kconfig

Expose CONF_GNRC_PKTBUF_SIZE to Kconfig

sys/net/gnrc/Kconfig

@@ -12,6 +12,7 @@ rsource "link_layer/lorawan/Kconfig"
 rsource "netif/Kconfig"
 rsource "network_layer/ipv6/Kconfig"
 rsource "network_layer/sixlowpan/Kconfig"
+rsource "pktbuf/Kconfig"
 rsource "pktdump/Kconfig"
 rsource "routing/rpl/Kconfig"
 rsource "transport_layer/tcp/Kconfig"

sys/net/gnrc/pktbuf/Kconfig

@@ -0,0 +1,24 @@
+# Copyright (c) 2020 Freie Universitaet Berlin
+#
+# This file is subject to the terms and conditions of the GNU Lesser
+# General Public License v2.1. See the file LICENSE in the top level
+# directory for more details.
+#
+menuconfig KCONFIG_MODULE_GNRC_PKTBUF
+    bool "Configure GNRC_PKTBUF"
+    depends on MODULE_GNRC_PKTBUF
+    help
+        Configure the GNRC_PKTBUF using Kconfig.
+
+if KCONFIG_MODULE_GNRC_PKTBUF
+
+config GNRC_PKTBUF_SIZE
+    int "Maximum size of the static packet buffer"
+    default 6144
+    help
+        Set the value to 0 to allow dynamic memory management to allocate
+        packets. The rational here is to have enough space for 4 full-MTU IPv6
+        packets (2 incoming, 2 outgoing; 2 * 2 * 1280 B = 5 KiB) + Meta-Data
+        (roughly estimated to 1 KiB; might be smaller).
+
+endif # KCONFIG_MODULE_GNRC_PKTBUF