Pages
About Me
Links
Tags
PERSONAL 520
SPIRITUAL 416
LDS 312
BOOK OF MORMON 237
SCRIPTURES 154
STUDIO-JOURNEY 129
RELIGION 112
LINUX 79
COMPUTERS 65
LIFE 60
GENERAL CONFERENCE 46
GENTOO 39
MISCELLANEOUS 37
MUSIC 37
PROGRAMMING 33
CARS 29
MICROSOFT 23
FAMILY 23
AUDIO 21
I LOVE MY JOURNAL 18
FUN 15
CHILDREN 12
CURRENT EVENTS 10
NATURE'S WAY 10
VIDEO 9
DRM 9
CONEXM 7
BABBLINGS 7
PROVO CITY CENTER TEMPLE 6
FRIENDS 6
HEROD THE FINK 5
GAMES 5
COMPUTER HARDWARE 5
DRUMS 4
HAND OF GOD 3
ADVERSITY 3
KDENLIVE 3
AUDIO HARDWARE 3
GENERAL INSANITY 3
STUDIO 3
THANKS4GIVING 2
CATS 2
MY JOURNAL 1
POETRY 1
FOREVERGREEN 1
EVERYDAY THOUGHTS 1
GOSPEL 1
PARENTING 1
YOUTH CONFERENCE 1
CHURCH NOTES 1
POLITICS 1
RSS Feed
Subscribe!Tue - Oct 16, 2007 : 10:22 am
anxious
 |
|
|
|
|
rated 0 times |
Gentoo udev NIC Bug
Something I thought I'd write down, because it took me forever to figure out, has been a bug for at least a year, and nobody seems to be doing anything about it.
The bug is quite simple really, and once you know where to look for it, it pretty much stops being a bug due to an extremely easy work-around.
The bug is concerning network cards plugged into a computer.
Usually, when you install gentoo, your network card is attached to a node which is controlled by the file /etc/init.d/net.eth0. Easy enough, right?
Well.. Let's say you remove your NIC (Network Interface Card) and replace it with a better one. You then try to fire it up by issuing a "/etc/init.d/net.eth0 start"
Your computer would then tell you, through cryptic language of course, that it can't find any hardware which can be controlled by net.eth0.
It has changed to net.eth1
The bug is, basically, that the net.lo never resets itself back to zero when a NIC is removed or replaced. So........
If you plug 20 NICs into your computer, one after another, removing the last, booting each one, the next nic you plug in will have to be initiated by controlling the net.eth21 file.
Nothing huge, but if you don't know about it, it can cause some serious headache.
The bug is quite simple really, and once you know where to look for it, it pretty much stops being a bug due to an extremely easy work-around.
The bug is concerning network cards plugged into a computer.
Usually, when you install gentoo, your network card is attached to a node which is controlled by the file /etc/init.d/net.eth0. Easy enough, right?
Well.. Let's say you remove your NIC (Network Interface Card) and replace it with a better one. You then try to fire it up by issuing a "/etc/init.d/net.eth0 start"
Your computer would then tell you, through cryptic language of course, that it can't find any hardware which can be controlled by net.eth0.
It has changed to net.eth1
The bug is, basically, that the net.lo never resets itself back to zero when a NIC is removed or replaced. So........
If you plug 20 NICs into your computer, one after another, removing the last, booting each one, the next nic you plug in will have to be initiated by controlling the net.eth21 file.
Nothing huge, but if you don't know about it, it can cause some serious headache.
Comment by Chris Harcourt on Oct. 16, 2007 @ 02:25 pm
I think I've fallen foul of this myself, without realising it. Thank's for the clarification.
Comment by Lonnie Olson on Oct. 16, 2007 @ 06:14 pm
This is not a bug... It's a feature!
This is caused because Gentoo comes with a udev rule "/etc/udev/rules.d/75-persistent-net-generator.rules" that records the MAC address of the card and forever ties that MAC address to the name it came up as (eth0). Any other cards can never use that name again. These associations are stored in the udev rule "/etc/udev/rules.d/70-persistent-net.rules". A simple fix is to remove the association from that file, and reboot. You could also delete the 75-persistent-net-generator rules file to prevent associations from ever being created.
There really is a good reason for this persistent network naming. It keeps your cards from changing their names. For example swapping card slots when using multiple cards would normally change the order, hence the network card name. Another example is USB, or Firewire network interfaces, with the udev rule in place you no longer have to worry about getting the right network interface name.
This is caused because Gentoo comes with a udev rule "/etc/udev/rules.d/75-persistent-net-generator.rules" that records the MAC address of the card and forever ties that MAC address to the name it came up as (eth0). Any other cards can never use that name again. These associations are stored in the udev rule "/etc/udev/rules.d/70-persistent-net.rules". A simple fix is to remove the association from that file, and reboot. You could also delete the 75-persistent-net-generator rules file to prevent associations from ever being created.
There really is a good reason for this persistent network naming. It keeps your cards from changing their names. For example swapping card slots when using multiple cards would normally change the order, hence the network card name. Another example is USB, or Firewire network interfaces, with the udev rule in place you no longer have to worry about getting the right network interface name.
Comment by PoeticIntensity on Oct. 16, 2007 @ 09:33 pm
@Lonnie
You're exactly right, however, most people aren't used to this "feature" when dealing with network cards. The gentoo handbook says nothing of this feature, either, so those people who think replacing their NICs will replace their respective files are gonna be quite confused. I personally know a person who is now a gentoo dev who also got bit by this...
"I swear I put that hardware in, and loaded the right kernel modules! Why the flip can't it be found now?" There's got to be a way of informing people of this bug / feature.
You're exactly right, however, most people aren't used to this "feature" when dealing with network cards. The gentoo handbook says nothing of this feature, either, so those people who think replacing their NICs will replace their respective files are gonna be quite confused. I personally know a person who is now a gentoo dev who also got bit by this...
"I swear I put that hardware in, and loaded the right kernel modules! Why the flip can't it be found now?" There's got to be a way of informing people of this bug / feature.