When upgrading some of my machines from FreeBSD 11 to FreeBSD 12, I found that some of them could not transfer data via Ethernet after the upgrade. ifconfig seemed to work normally, including showing "status: active", but that interface could neither send nor receive data packets, no matter what I tried. And a few minutes after booting my systems, they would silently hang, with no response whatsoever, even on a serial console. I eventually narrowed down the problem to my machines with Intel 82547GI chips, which look like this in "pciconf -lv": em0@pci0:1:1:0: class=0x020000 card=0x10758086 chip=0x10758086 rev=0x00 hdr=0x00 vendor = 'Intel Corporation' device = '82547GI Gigabit Ethernet Controller' class = network subclass = ethernet By comparing the FreeBSD 11 code (which I knew worked) with the FreeBSD 12 code which had the problem, I found the solution: the 82547 is an "edge" case which slipped through the cracks when the Intel em driver was modified for FreeBSD 12. Here is what I had to change in if_em.c to make the Intel 82547 Ethernet chips work: root@prod:~ # svn diff /usr/src/sys/dev/e1000/if_em.c Index: /usr/src/sys/dev/e1000/if_em.c =================================================================== --- /usr/src/sys/dev/e1000/if_em.c (revision 344229) +++ /usr/src/sys/dev/e1000/if_em.c (working copy) @@ -31,13 +31,16 @@ #include <sys/sbuf.h> #include <machine/_inttypes.h> -#define em_mac_min e1000_82547 +// jagwas: #define em_mac_min e1000_82547 +#define em_mac_min e1000_82571 // jag; 25feb2019; + // so (adapter->hw.mac.type < em_mac_min) + // is true for 82547GI and below #define igb_mac_min e1000_82575 /********************************************************************* * Driver version: *********************************************************************/ -char em_driver_version[] = "7.6.1-k"; +char em_driver_version[] = "7.6.1-k+jag3"; /********************************************************************* * PCI Device ID Table @@ -2476,6 +2479,24 @@ case e1000_i211: pba = E1000_PBA_34K; break; + // jag; 26feb2019 added this case section; adapted from + // FreeBSD 11 /usr/src/sys/dev/e1000/if_lem.c + case e1000_82547: + case e1000_82547_rev_2: /* 82547: Total Packet Buffer is 40K */ + if (adapter->hw.mac.max_frame_size > 8192) + pba = E1000_PBA_22K; /* 22K for Rx, 18K for Tx */ + else + pba = E1000_PBA_30K; /* 30K for Rx, 10K for Tx */ + + // jag; the following would be needed for plain 82547 (before GI) + // and would also require adding the elements set here to + // struct adapter in if_em.h: + // adapter->tx_fifo_head = 0; + // adapter->tx_head_addr = pba << EM_TX_HEAD_ADDR_SHIFT; + // adapter->tx_fifo_size = + // (E1000_PBA_40K - pba) << EM_PBA_BYTES_SHIFT; + + break; default: if (adapter->hw.mac.max_frame_size > 8192) pba = E1000_PBA_40K; /* 40K for Rx, 24K for Tx */ root@prod:~ # With that change, my interfaces all now work fine, and my systems don't hang (I think the hanging problem was because the pre-change if_em.c was assigning more packet buffer space than the 82547GI actually has). I believe this change will also help some of the other 82547 models to work, but I don't have any of those chips and so cannot test them. Those chips also seem to need some workarounds for special cases (like jumbo frames which cross buffer boundaries); those workarounds are implemented in FreeBSD 11 but not in FreeBSD 12, and I didn't implement them as part of this change because my 82547GI chip doesn't need them. (For example, see the lem_82547_fifo_workaround() function; search for "82547" in the /usr/src/sys/dev/e1000/if_lem.c file in FreeBSD 11 to see other workarounds). This problem seems to exist on CURRENT, too (from looking at the code; I have not tested that).