From 635dc3f7ffc279095d5e971d785578849c72db95 Mon Sep 17 00:00:00 2001
From: Nathan Whitehorn <nwhitehorn@FreeBSD.org>
Date: Sun, 18 Oct 2009 17:11:16 +0000
Subject: [PATCH] Work around a quirk with the G5 Xserve, which has a fake GMAC
 controller with an all-zero MAC address. In this case, don't attach.

Discussed with:	marius
---
 sys/dev/gem/if_gem_pci.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/sys/dev/gem/if_gem_pci.c b/sys/dev/gem/if_gem_pci.c
index 05be3236ca7e..051dbcc5bfbd 100644
--- a/sys/dev/gem/if_gem_pci.c
+++ b/sys/dev/gem/if_gem_pci.c
@@ -295,6 +295,16 @@ gem_pci_attach(device_t dev)
 	    GEM_PCI_ROM_OFFSET + j + PCI_VPDRES_LARGE_SIZE + PCI_VPD_SIZE,
 	    sc->sc_enaddr, ETHER_ADDR_LEN);
 #endif
+	/*
+	 * The Xserve G5 has a fake GMAC with an all-zero MAC address.
+	 * Check for this, and don't attach in this case.
+	 */
+
+	for (i = 0; i < ETHER_ADDR_LEN && sc->sc_enaddr[i] == 0; i++) {}
+	if (i == ETHER_ADDR_LEN) {
+		device_printf(dev, "invalid MAC address\n");
+		goto fail;
+	}
 
 	if (gem_attach(sc) != 0) {
 		device_printf(dev, "could not be attached\n");