[netdevice] Add the concept of an "Ethernet-compatible" MAC address

The iBFT is Ethernet-centric in providing only six bytes for a MAC
address.  This is most probably an indirect consequence of a similar
design flaw in the Windows NDIS stack.  (The WinOF IPoIB stack
performs all sorts of contortions in order to pretend to the NDIS
layer that it is dealing with six-byte MAC addresses.)

There is no sensible way in which to extend the iBFT without breaking
compatibility with programs that expect to parse it.  Add the notion
of an "Ethernet-compatible" MAC address to our link layer abstraction,
so that link layers can provide their own workarounds for this
limitation.

2 files changed, 14 insertions, 6 deletions

diff --git a/src/include/gpxe/ethernet.h b/src/include/gpxe/ethernet.h
index 8cf6b1be7..4dfc24d3f 100644
--- a/src/include/gpxe/ethernet.h
+++ b/src/include/gpxe/ethernet.h
@@ -15,6 +15,7 @@ extern void eth_init_addr ( const void *hw_addr, void *ll_addr );
 extern const char * eth_ntoa ( const void *ll_addr );
 extern int eth_mc_hash ( unsigned int af, const void *net_addr,
 			 void *ll_addr );
+extern int eth_eth_addr ( const void *ll_addr, void *eth_addr );
 extern struct net_device * alloc_etherdev ( size_t priv_size );
 
 #endif /* _GPXE_ETHERNET_H */
diff --git a/src/include/gpxe/netdevice.h b/src/include/gpxe/netdevice.h
index fd77d893a..858d8e97d 100644
--- a/src/include/gpxe/netdevice.h
+++ b/src/include/gpxe/netdevice.h
@@ -128,8 +128,8 @@ struct ll_protocol {
 	/**
 	 * Transcribe link-layer address
 	 *
-	 * @v ll_addr	Link-layer address
-	 * @ret string	Human-readable transcription of address
+	 * @v ll_addr		Link-layer address
+	 * @ret string		Human-readable transcription of address
 	 *
 	 * This method should convert the link-layer address into a
 	 * human-readable format.
@@ -141,13 +141,20 @@ struct ll_protocol {
 	/**
 	 * Hash multicast address
 	 *
-	 * @v af	Address family
-	 * @v net_addr	Network-layer address
-	 * @v ll_addr	Link-layer address to fill in
-	 * @ret rc	Return status code
+	 * @v af		Address family
+	 * @v net_addr		Network-layer address
+	 * @v ll_addr		Link-layer address to fill in
+	 * @ret rc		Return status code
 	 */
 	int ( * mc_hash ) ( unsigned int af, const void *net_addr,
 			    void *ll_addr );
+	/**
+	 * Generate Ethernet-compatible compressed link-layer address
+	 *
+	 * @v ll_addr		Link-layer address
+	 * @v eth_addr		Ethernet-compatible address to fill in
+	 */
+	int ( * eth_addr ) ( const void *ll_addr, void *eth_addr );
 	/** Link-layer protocol
 	 *
 	 * This is an ARPHRD_XXX constant, in network byte order.