Disable the use of Jumbo frames on the first generation chips (82542).

The exact details are unknown (possibly hw errata?) but the Windows
and Linux drivers have never supported Jumbos on this chipset and since
it is so old and rare it is not that big of a deal.

From FreeBSD

ok dlg@ awhile ago.

diff --git a/sys/dev/pci/if_em.c b/sys/dev/pci/if_em.c
index 459b507..a4ebc80 100644 (file)
--- a/sys/dev/pci/if_em.c
+++ b/sys/dev/pci/if_em.c
@@ -31,7 +31,7 @@ POSSIBILITY OF SUCH DAMAGE.
 
 ***************************************************************************/
 
-/* $OpenBSD: if_em.c,v 1.186 2008/07/15 17:50:20 kettenis Exp $ */
+/* $OpenBSD: if_em.c,v 1.187 2008/08/29 23:28:34 brad Exp $ */
 /* $FreeBSD: if_em.c,v 1.46 2004/09/29 18:28:28 mlaier Exp $ */
 
 #include <dev/pci/if_em.h>
@@ -315,8 +315,10 @@ em_attach(struct device *parent, struct device *self, void *aux)
                case em_80003es2lan:    /* Limit Jumbo Frame size */
                        sc->hw.max_frame_size = 9234;
                        break;
+                       /* Adapters that do not support Jumbo frames */
+               case em_82542_rev2_0:
+               case em_82542_rev2_1:
                case em_ich8lan:
-                       /* ICH8 does not support jumbo frames */
                        sc->hw.max_frame_size = ETHER_MAX_LEN;
                        break;
                default: