[tables] Redefine methods for accessing linker tables

Intel's C compiler (icc) chokes on the zero-length arrays that we
currently use as part of the mechanism for accessing linker table
entries.  Abstract away the zero-length arrays, to make a port to icc
easier.

Introduce macros such as for_each_table_entry() to simplify the common
case of iterating over all entries in a linker table.

Represent table names as #defined string constants rather than
unquoted literals; this avoids visual confusion between table names
and C variable or type names, and also allows us to force a
compilation error in the event of incorrect table names.

4 files changed, 7 insertions, 36 deletions

diff --git a/src/net/arp.c b/src/net/arp.c
index ba9ebf488..cf2fe988d 100644
--- a/src/net/arp.c
+++ b/src/net/arp.c
@@ -36,12 +36,6 @@
  *
  */
 
-/** Registered ARP protocols */
-static struct arp_net_protocol arp_net_protocols[0]
-	__table_start ( struct arp_net_protocol, arp_net_protocols );
-static struct arp_net_protocol arp_net_protocols_end[0]
-	__table_end ( struct arp_net_protocol, arp_net_protocols );
-
 /** An ARP cache entry */
 struct arp_entry {
 	/** Network-layer protocol */
@@ -176,8 +170,7 @@ int arp_resolve ( struct net_device *netdev, struct net_protocol *net_protocol,
 static struct arp_net_protocol * arp_find_protocol ( uint16_t net_proto ) {
 	struct arp_net_protocol *arp_net_protocol;
 
-	for ( arp_net_protocol = arp_net_protocols ;
-	      arp_net_protocol < arp_net_protocols_end ; arp_net_protocol++ ) {
+	for_each_table_entry ( arp_net_protocol, ARP_NET_PROTOCOLS ) {
 		if ( arp_net_protocol->net_protocol->net_proto == net_proto ) {
 			return arp_net_protocol;
 		}
diff --git a/src/net/netdevice.c b/src/net/netdevice.c
index 9e142d274..9e0314973 100644
--- a/src/net/netdevice.c
+++ b/src/net/netdevice.c
@@ -36,12 +36,6 @@
  *
  */
 
-/** Registered network-layer protocols */
-static struct net_protocol net_protocols[0]
-	__table_start ( struct net_protocol, net_protocols );
-static struct net_protocol net_protocols_end[0]
-	__table_end ( struct net_protocol, net_protocols );
-
 /** List of network devices */
 struct list_head net_devices = LIST_HEAD_INIT ( net_devices );
 
@@ -538,8 +532,7 @@ int net_rx ( struct io_buffer *iobuf, struct net_device *netdev,
 	struct net_protocol *net_protocol;
 
 	/* Hand off to network-layer protocol, if any */
-	for ( net_protocol = net_protocols ; net_protocol < net_protocols_end ;
-	      net_protocol++ ) {
+	for_each_table_entry ( net_protocol, NET_PROTOCOLS ) {
 		if ( net_protocol->net_proto == net_proto ) {
 			return net_protocol->rx ( iobuf, netdev, ll_source );
 		}
diff --git a/src/net/tcpip.c b/src/net/tcpip.c
index d4542b05b..cef638f34 100644
--- a/src/net/tcpip.c
+++ b/src/net/tcpip.c
@@ -14,18 +14,6 @@
  * TCP/IP transport-network layer interface
  */
 
-/** Registered network-layer protocols that support TCP/IP */
-static struct tcpip_net_protocol tcpip_net_protocols[0]
-	__table_start ( struct tcpip_net_protocol, tcpip_net_protocols );
-static struct tcpip_net_protocol tcpip_net_protocols_end[0]
-	__table_end ( struct tcpip_net_protocol, tcpip_net_protocols );
-
-/** Registered transport-layer protocols that support TCP/IP */
-static struct tcpip_protocol tcpip_protocols[0]
-	__table_start ( struct tcpip_protocol, tcpip_protocols );
-static struct tcpip_protocol tcpip_protocols_end[0]
-	__table_end ( struct tcpip_protocol, tcpip_protocols );
-
 /** Process a received TCP/IP packet
  *
  * @v iobuf		I/O buffer
@@ -48,7 +36,7 @@ int tcpip_rx ( struct io_buffer *iobuf, uint8_t tcpip_proto,
 	struct tcpip_protocol *tcpip;
 
 	/* Hand off packet to the appropriate transport-layer protocol */
-	for ( tcpip = tcpip_protocols; tcpip < tcpip_protocols_end; tcpip++ ) {
+	for_each_table_entry ( tcpip, TCPIP_PROTOCOLS ) {
 		if ( tcpip->tcpip_proto == tcpip_proto ) {
 			DBG ( "TCP/IP received %s packet\n", tcpip->name );
 			return tcpip->rx ( iobuf, st_src, st_dest, pshdr_csum );
@@ -76,8 +64,7 @@ int tcpip_tx ( struct io_buffer *iobuf, struct tcpip_protocol *tcpip_protocol,
 	struct tcpip_net_protocol *tcpip_net;
 
 	/* Hand off packet to the appropriate network-layer protocol */
-	for ( tcpip_net = tcpip_net_protocols ;
-	      tcpip_net < tcpip_net_protocols_end ; tcpip_net++ ) {
+	for_each_table_entry ( tcpip_net, TCPIP_NET_PROTOCOLS ) {
 		if ( tcpip_net->sa_family == st_dest->st_family ) {
 			DBG ( "TCP/IP sending %s packet\n", tcpip_net->name );
 			return tcpip_net->tx ( iobuf, tcpip_protocol, st_src,
diff --git a/src/net/udp/dhcp.c b/src/net/udp/dhcp.c
index ab843ce1d..0f4459956 100644
--- a/src/net/udp/dhcp.c
+++ b/src/net/udp/dhcp.c
@@ -88,10 +88,6 @@ static uint8_t dhcp_request_options_data[] = {
 	DHCP_END
 };
 
-/** DHCP feature codes */
-static uint8_t dhcp_features[0] __table_start ( uint8_t, dhcp_features );
-static uint8_t dhcp_features_end[0] __table_end ( uint8_t, dhcp_features );
-
 /** Version number feature */
 FEATURE_VERSION ( VERSION_MAJOR, VERSION_MINOR, VERSION_PATCH );
 
@@ -884,6 +880,7 @@ int dhcp_create_request ( struct dhcp_packet *dhcppkt,
 	struct dhcp_netdev_desc dhcp_desc;
 	struct dhcp_client_id client_id;
 	struct dhcp_client_uuid client_uuid;
+	uint8_t *dhcp_features;
 	size_t dhcp_features_len;
 	size_t ll_addr_len;
 	ssize_t len;
@@ -903,7 +900,8 @@ int dhcp_create_request ( struct dhcp_packet *dhcppkt,
 	dhcppkt->dhcphdr->ciaddr = ciaddr;
 
 	/* Add options to identify the feature list */
-	dhcp_features_len = ( dhcp_features_end - dhcp_features );
+	dhcp_features = table_start ( uint8_t, DHCP_FEATURES );
+	dhcp_features_len = table_num_entries ( uint8_t, DHCP_FEATURES );
 	if ( ( rc = dhcppkt_store ( dhcppkt, DHCP_EB_ENCAP, dhcp_features,
 				    dhcp_features_len ) ) != 0 ) {
 		DBG ( "DHCP could not set features list option: %s\n",