Completes conversion of CONFIG_NET_BUFIZE to CONFIG_NET_ETH/SLIP_MTU

net/Kconfig

@@ -47,25 +47,38 @@ config NET_PROMISCUOUS
 		Force the Ethernet driver to operate in promiscuous mode (if supported
 		by the Ethernet driver).
 
-config NET_BUFSIZE
-	int "Network packet buffer size (MTU)"
-	default 1294 if !NET_SLIP && NET_IPv6
-	default 590 if !NET_SLIP && !NET_IPv6
-	default 296 if NET_SLIP && !NET_IPv6
+config NET_ETH_MTU
+	int "Ethernet packet buffer size (MTU)"
+	default 1294 if NET_IPv6
+	default 590 if !NET_IPv6
+	depends on NET_ETHERNET
+	range 590 1518
 	---help---
 		Packet buffer size.  This size includes the TCP/UDP payload plus the
-		size of TCP/UDP header, the IP header, and the Ethernet header
-		(assuming that the Ethernet transport is used).  This value is
-		normally referred to as the MTU (Maximum Transmission Unit); the
-		payload is the MSS (Maximum Segment Size).
+		size of TCP/UDP header, the IP header, and the Ethernet header.
+		This value is normally referred to as the MTU (Maximum Transmission
+		Unit); the payload is the MSS (Maximum Segment Size).
 
 		IPv4 hosts are required to be able to handle an MSS of at least
 		536 octets, resulting in a minimum buffer size of 536+20+20+14 =
-		590 (For SLIP 256+20+20 = 296).
+		590.
 
 		IPv6 hosts are required to be able to handle an MSS of 1220 octets,
 		resulting in a minimum buffer size of of 1220+20+40+14 = 1294
 
+config NET_SLIP_MTU
+	int # "SLIP packet buffer size (MTU)"
+	default 296
+	depends on NET_SLIP
+	range 296 1518
+	---help---
+		Packet buffer size.  This size includes the TCP/UDP payload plus the
+		size of TCP/UDP header and the IP header.  This value is normally
+		referred to as the MTU (Maximum Transmission Unit); the payload
+		payload is the MSS (Maximum Segment Size).  SLIP is required to
+		support at lest 256+20+20 = 296.  Values other than 296 are not
+		recommended.
+
 config NET_RECEIVE_WINDOW
 	int "Receive window size"
 	default 1220 if !NET_SLIP && NET_IPv6
@@ -115,10 +128,6 @@ config NET_SLIP
 		at least one IP protocol selected and the following additional
 		network settings: NET_NOINTS and NET_MULTIBUFFER.
 
-		NET_BUFSIZE *must* be set to 296.  Other optional configuration
-		settings that affect the SLIP driver: NET_STATISTICS.
-		Default: Ethernet
-
 		SLIP supports point-to-point IP communications over a serial port.
 		The default data link layer for uIP is Ethernet. If NET_SLIP is
 		defined in the NuttX configuration file, then SLIP will be supported.

net/devif/devif_input.c

@@ -113,7 +113,7 @@
 /* IP fragment re-assembly */
 
 #define IP_MF                0x20
-#define TCP_REASS_BUFSIZE    (CONFIG_NET_BUFSIZE - NET_LL_HDRLEN(dev))
+#define TCP_REASS_BUFSIZE    (NET_LL_MTU(dev) - NET_LL_HDRLEN(dev))
 #define TCP_REASS_LASTFRAG   0x01
 
 /****************************************************************************

net/devif/devif_iobsend.c

@@ -99,7 +99,7 @@
 void devif_iob_send(FAR struct net_driver_s *dev, FAR struct iob_s *iob,
                     unsigned int len, unsigned int offset)
 {
-  DEBUGASSERT(dev && len > 0 && len < CONFIG_NET_BUFSIZE);
+  DEBUGASSERT(dev && len > 0 && len < NET_LL_MTU(dev));
 
   /* Copy the data from the I/O buffer chain to the device buffer */
 

net/devif/devif_pktsend.c

@@ -99,7 +99,7 @@
 void devif_pkt_send(FAR struct net_driver_s *dev, FAR const void *buf,
                     unsigned int len)
 {
-  DEBUGASSERT(dev && len > 0 && len < CONFIG_NET_BUFSIZE);
+  DEBUGASSERT(dev && len > 0 && len < NET_LL_MTU(dev));
 
   /* Copy the data into the device packet buffer */
 

net/devif/devif_send.c

@@ -94,7 +94,7 @@
 
 void devif_send(struct net_driver_s *dev, const void *buf, int len)
 {
-  DEBUGASSERT(dev && len > 0 && len < CONFIG_NET_BUFSIZE);
+  DEBUGASSERT(dev && len > 0 && len < NET_LL_MTU(dev));
 
   memcpy(dev->d_snddata, buf, len);
   dev->d_sndlen = len;

net/netdev/netdev_ioctl.c

@@ -316,8 +316,12 @@ static int netdev_ifrioctl(FAR struct socket *psock, int cmd,
 
       case SIOCGIFMTU:  /* Get MTU size */
         {
-          req->ifr_mtu = CONFIG_NET_BUFSIZE;
-          ret = OK;
+          dev = netdev_ifrdev(req);
+          if (dev)
+            {
+              req->ifr_mtu = NET_LL_MTU(dev);
+              ret = OK;
+            }
         }
         break;
 

net/tcp/Kconfig

@@ -31,7 +31,7 @@ config NET_TCP_REASSEMBLY
 		This features requires an additional amount of RAM to hold the
 		reassembly buffer and the reassembly code size is approximately 700
 		bytes.  The reassembly buffer is of the same size as the d_buf buffer
-		(configured by CONFIG_NET_BUFSIZE).
+		(configured by CONFIG_NET_xxx_MTU).
 
 		Note: IP packet reassembly is not heavily tested (and, hence,
 		EXPERIMENTAL).

net/utils/net_chksum.c

@@ -128,7 +128,7 @@ static uint16_t upper_layer_chksum(FAR struct net_driver_s *dev, uint8_t proto)
 
   /* Verify some minimal assumptions */
 
-  if (upper_layer_len > CONFIG_NET_BUFSIZE)
+  if (upper_layer_len > NET_LL_MTU(dev))
     {
       return 0;
     }