-
Junior Member
registered user
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
Posting Permissions
- You may not post new threads
- You may not post replies
- You may not post attachments
- You may not edit your posts
-
Forum Rules
Vintage Apple Disk II Analog Card 820-0007
$50.00
Vintage Intel Pentium Pro 200 MHz 256K KB80521EX200 SL22V Socket 8 Collectible
$30.00
Vintage Macintosh 512k Motherboard With 800K Roms Tested Working 512ke Computer
$79.00
386DX Intel A80386DX-25 IV SX543 386 25Mhz vintage CPU GOLD
$13.99
Vintage 1980’s APPLE Computer Rainbow Logo Window Cling DECAL Unused.
$9.99
VINTAGE IBM Thinkpad T43 Laptop- Intel Pentium M 1.73GHz 2GB RAM 37GB HDD WIN XP
$125.00
VINTAGE DELL INSPIRON B130 WINDOWS XP HOME LAPTOP DVD WIRELESS Needs 2 Keys Wrks
$80.00
Vintage Classic Apple Macintosh System Boot Install Disk Floppy/CD *Pick Version
$10.39
Vintage HP Pavilion 7915 MT Intel Celeron 1.10GHz 128MB RAM 40 GB HDD Windows XP
$79.99
Vintage Dell Precision 410 Intel Pentium II 600 MHz 768 MB Ram I No HDD I No OS
$129.99