[PATCH 3/3] Use UEFI MAC device as default configured by net_bootp6

[Michael Chang]

The grub_efinet_findcards will register cards by checking if it can support EFI
Simple Netowork Protocol which create more than one device to a physical NIC
device.

If without specifying any device to be configured by net_bootp6, it should pick
up one from them but not all. In my case three firmware device are listed.
IPv4, IPv6 and MAC device. Both IPv4 and IPv6 are derived from MAC device for
providing PXE Base Code Protocol. I think we should use MAC device instead of
those two to avoid collision, because net_bootp6 command does not depend on PXE
Base Code but only Simple Network Protocol to work
---
 grub-core/net/bootp.c              |    8 +++++++
 grub-core/net/drivers/efi/efinet.c |   40 ++++++++++++++++++++++++++++++++++++
 include/grub/net.h                 |    1 +
 3 files changed, 49 insertions(+), 0 deletions(-)

diff --git a/grub-core/net/bootp.c b/grub-core/net/bootp.c
index 477f205..c4963ca 100644
--- a/grub-core/net/bootp.c
+++ b/grub-core/net/bootp.c
@@ -1290,6 +1290,10 @@ grub_cmd_bootp6 (struct grub_command *cmd __attribute__ 
((unused)),
   {
     if (argc > 0 && grub_strcmp (card->name, args[0]) != 0)
       continue;
+#ifdef GRUB_MACHINE_EFI
+    else if (!card->is_efi_mac_device (card))
+      continue;
+#endif
     ncards++;
   }
 
@@ -1299,6 +1303,10 @@ grub_cmd_bootp6 (struct grub_command *cmd __attribute__ 
((unused)),
 
     if (argc > 0 && grub_strcmp (card->name, args[0]) != 0)
       continue;
+#ifdef GRUB_MACHINE_EFI
+    else if (!card->is_efi_mac_device (card))
+      continue;
+#endif
 
     ifaces = grub_net_ipv6_get_link_local (card, &card->default_address);
     if (!ifaces)
diff --git a/grub-core/net/drivers/efi/efinet.c 
b/grub-core/net/drivers/efi/efinet.c
index b1837e3..900384f 100644
--- a/grub-core/net/drivers/efi/efinet.c
+++ b/grub-core/net/drivers/efi/efinet.c
@@ -157,6 +157,45 @@ grub_efinet_get_device_handle (struct grub_net_card *card)
   return card->efi_handle;
 }
 
+static int
+grub_efinet_is_mac_device (struct grub_net_card *card)
+{
+  grub_efi_handle_t efi_handle;
+  grub_efi_device_path_t *dp;
+  grub_efi_device_path_t *next, *p;
+  grub_efi_uint8_t type;
+  grub_efi_uint8_t subtype;
+
+  efi_handle = grub_efinet_get_device_handle (card);
+
+  if (!efi_handle)
+    return 0;
+
+  dp = grub_efi_get_device_path (efi_handle);
+
+  if (GRUB_EFI_END_ENTIRE_DEVICE_PATH (dp))
+    return 0;
+
+  for (p = (grub_efi_device_path_t *) dp, next = GRUB_EFI_NEXT_DEVICE_PATH (p);
+       ! GRUB_EFI_END_ENTIRE_DEVICE_PATH (next);
+       p = next, next = GRUB_EFI_NEXT_DEVICE_PATH (next))
+    ;
+
+  if (p)
+    {
+      type = GRUB_EFI_DEVICE_PATH_TYPE (p);
+      subtype = GRUB_EFI_DEVICE_PATH_SUBTYPE (p);
+
+      if (type == GRUB_EFI_MESSAGING_DEVICE_PATH_TYPE
+         && subtype == GRUB_EFI_MAC_ADDRESS_DEVICE_PATH_SUBTYPE)
+       {
+         return 1;
+       }
+    }
+
+  return 0;
+}
+
 static void
 grub_efinet_findcards (void)
 {
@@ -223,6 +262,7 @@ grub_efinet_findcards (void)
                   sizeof (card->default_address.mac));
       card->efi_net = net;
       card->efi_handle = *handle;
+      card->is_efi_mac_device = grub_efinet_is_mac_device;
 
       grub_net_card_register (card);
     }
diff --git a/include/grub/net.h b/include/grub/net.h
index 71dc243..4571b72 100644
--- a/include/grub/net.h
+++ b/include/grub/net.h
@@ -140,6 +140,7 @@ struct grub_net_card
       struct grub_efi_simple_network *efi_net;
       grub_efi_handle_t efi_handle;
       grub_size_t last_pkt_size;
+      int (*is_efi_mac_device) (struct grub_net_card* card);
     };
 #endif
     void *data;
-- 
1.7.3.4