[ecm] Use ACPI-provided system-specific MAC address if present Use the "system MAC address" provided within the DSDT/SSDT if such an address is available and has not already been assigned to a network device. Tested-by: Andreas Hammarskjöld <junior@2PintSoftware.com> Signed-off-by: Michael Brown <mcb30@ipxe.org>

diff --git a/src/drivers/net/ecm.c b/src/drivers/net/ecm.c
index 9160498..2f784d5 100644
--- a/src/drivers/net/ecm.c
+++ b/src/drivers/net/ecm.c

@@ -30,6 +30,7 @@
 #include <ipxe/if_ether.h>
 #include <ipxe/base16.h>
 #include <ipxe/profile.h>
+#include <ipxe/acpimac.h>
 #include <ipxe/usb.h>
 #include "ecm.h"
 
@@ -93,6 +94,14 @@
 	int len;
 	int rc;
 
+	/* Use system-specific MAC address, if present and not already used */
+	if ( ( ( rc = acpi_mac ( hw_addr ) ) == 0 ) &&
+	     ! find_netdev_by_ll_addr ( &ethernet_protocol, hw_addr ) ) {
+		DBGC ( usb, "USB %s using system-specific MAC %s\n",
+		       func->name, eth_ntoa ( hw_addr ) );
+		return 0;
+	}
+
 	/* Fetch MAC address string */
 	len = usb_get_string_descriptor ( usb, desc->mac, 0, buf,
 					  sizeof ( buf ) );