Results 1 to 3 of 3

Thread: Update the init script for multiple nics?

  1. #1
    Junior Member registered user
    Join Date
    Jan 2008
    Posts
    20

    Update the init script for multiple nics?

    I had a weird issue show up the other day. I am using Knoppix 6.7.0 to do PXE booting. I cannot use 6.7.1 at this time, so I do not know if this is fixed there.

    Client -> Knoppix 6.7
    Server -> Fedora 14. PXE files from Knoppix 6.7 CD.

    problem:
    Have an old machine with onboard 1 Gig nic, and pci 10/100 nic. Ethernet cord is plugged into onboard nic, boots, gets IP, TFTP Starts, select the kernel and go. Kernel loads, gets to the udhcp part of getting an IP. Times out.

    Playing with it, I re-started the process, and when udhcp was trying to get an ip, I moved the ethernet cord to the 10/100 pci nic. Knoppix found an ip and completed booting.

    Investigating further, it comes to show that the pci 10/100 board was grabbing eth0, and not the onboard Nic!

    Further investigation shows that the kernels attempt to load drivers in parallel, and that the ethX numbering scheme is based in part, on driver load order. Therefore, I can't really force that, and I'm also in an environment of lots of machines, so it's not like I can do a simple fix for 1 and be done.

    I then unpacked the minirt.gz and examined the init script. The issue is in the DHCP loop, it calls ifconfig up ethX. If ifconfig returns a non zero number, it is supposed to continue. For some reason, (driver? ifconfig bug?) calling ifconfig on eth0 (with no cord) results in a "ok" response.

    I have seen ifconfig up seem to "work" before on nics without a cord. So i suspect that it's not safe to depend on the return from it. I decided to change the init code to instead check for the presence of the cable using the /sys/class/net/ethX/operstate file.

    Works like a charm. I wanted to share the issue here, along with the code I did to change it, and see about putting that into future versions. I don't know how easy it will be to reproduce this, i saw it happen 18 times out of several hundred machines.

    note: my logic checks for the word "down" in the operstate file. I do not check for up, as there are a couple of other possible values, which may indicate there is a cord there. but it's always down when its down.

    I also check for the existence of the file, as ifconfig does not even raise an error doing "up" on a non-existent interface, like eth2. maybe ifconfig just needs to be upgraded, it seems pretty dumb.

    I just did ifconfig --version, and for Knoppix 6.7, it shows net-tools: 1.60 and ifconfig 1.42 (2001-04-13)

    Anyway, the fix:
    open init, search for DHCP and replace that part with this:


    Code:
    DHCP=""
     # How many network cards should we probe for?
     for i in 0 1 2 3; do
      ifconfig "eth$i" up >/dev/null 2>&1 || continue
      sleep 2
      if [ -f /sys/class/net/eth$i/operstate ]; then
              if grep -Fq "down" /sys/class/net/eth$i/operstate
              then
                continue
              fi
      else
        continue
      fi
     
      message "${CRE}${BLUE}DHCP Broadcasting for IP address (${MAGENTA}eth$i${BLUE})... ${NORMAL}"
      if [ -n "$HOSTNAME" ]; then
       udhcpc -i eth$i -H $HOSTNAME && DHCP="eth$i"
      else
       udhcpc -i eth$i && DHCP="eth$i"
      fi
      [ -n "$DHCP" ] && break
      message "${RED}No answer from network.${NORMAL}"
     done

  2. #2
    Junior Member registered user
    Join Date
    Jan 2008
    Posts
    20
    maybe we should move this to the remastering forum or something.

    But I am now seeing an issue "sometimes" with single card nics. Seems that the driver is slow to load or something? I sleep 4 seconds, but it still says cable is "down" and then like 5 seconds later a message pops up from the driver about TX and RX speeds. and by then the operstate is up.

    Guh...

  3. #3
    Junior Member
    Join Date
    Jul 2012
    Posts
    1
    Keeger,
    Can you let me know which file I need to update the init code? I have a same issues and I need this fix soon.

    thanks
    kevinn

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  


IBM System X3250 M3 Server 8GB RAM Intel Xeon x3440 2.53ghz (NO HDD) picture

IBM System X3250 M3 Server 8GB RAM Intel Xeon x3440 2.53ghz (NO HDD)

$41.99



IBM EServer Xseries 220 Desktop Computer Intel Pentium 3 1GHz 512MB Ram No HDD picture

IBM EServer Xseries 220 Desktop Computer Intel Pentium 3 1GHz 512MB Ram No HDD

$224.99



IBM Power S822 8284-22A 12SFF Power8 3.89GHz 6Core 64GB RAM No HDD Server System picture

IBM Power S822 8284-22A 12SFF Power8 3.89GHz 6Core 64GB RAM No HDD Server System

$314.99



1U IBM x3550 M5 4 Bay SFF SAS3 Server 2x E5-2683 V3 28 Core 128GB DDR4 2x Tray picture

1U IBM x3550 M5 4 Bay SFF SAS3 Server 2x E5-2683 V3 28 Core 128GB DDR4 2x Tray

$318.00



IBM Server Rack Cabinet Machine Type 9308 Model 42P w/ Mounting Accessories picture

IBM Server Rack Cabinet Machine Type 9308 Model 42P w/ Mounting Accessories

$379.99



IBM System x3550 M3 Dual Intel Xeon X5650 @2.67GHz 32GB RAM No HDD picture

IBM System x3550 M3 Dual Intel Xeon X5650 @2.67GHz 32GB RAM No HDD

$68.50



IBM System x3250 M3 4251PAB Server Intel Xeon X3430 2.4GHz 4GB SEE NOTES picture

IBM System x3250 M3 4251PAB Server Intel Xeon X3430 2.4GHz 4GB SEE NOTES

$21.41



IBM 9009-41A Power S914 w/ IBM Power9 CPU Processor 02CY259 9314 CA PQ NO RAM  picture

IBM 9009-41A Power S914 w/ IBM Power9 CPU Processor 02CY259 9314 CA PQ NO RAM

$2000.00



IBM QRadar xx29 Server 4412Q2A picture

IBM QRadar xx29 Server 4412Q2A

$209.99



IBM QRadar 1501 G3 Server picture

IBM QRadar 1501 G3 Server

$167.99