[blfs-support] Persistent device names problem.

Bruce Dubbs bruce.dubbs at gmail.com
Fri Nov 2 11:39:28 PDT 2012


pete wrote:
> Hi,
> I am not sure if this should be under LFS but it only showed up when I
> was well into the BLFS build.
>
> My PC is an x86 32bit m/c with a USB Cable Modem for the internet
> and an ethernet connection to a second PC.
>
> I have built LFS-7.2 (which includes udev-188 and kernel-3.5.2)
> plus BLFS Xorg-7.7-1 and Firefox-15.0.1 which is all working
> OK. The problem shows up when I boot up with the USB Cable Modem
> connected.
>
> On booting, the ethernet connection is named eth0 and the USB
> Cable Modem is named eth1. This would be fine, but the file
> /etc/udev/rules.d/70-persistent-net.rules which should
> swap the names does not run, meaning the interfaces cannot be
> configured.
>
> If I disconnect the USB Cable Modem before booting, the ethernet
> connection is named eth0 as before, but then (as expected) the file
> /etc/udev/rules.d/70-persistent-net.rules runs and
> renames it to eth1. I can then connect the USB Cable Modem,
> start the interface with "ifup eth0" and everything works OK.
>
> This system has been working OK using LFS-7.0, udev-173 and kernel-3.1.
>
> It appears that when the USB Cable Modem is detected, something
> prevents the file 70-persistent-net.rules from running.
>
> Any suggestions on how to trace the problem would be appreciated.
>
> Pete.
>
> ============================
>
> Below I have added the dmesg outputs for booting with and without the
> USB Cable Modem connected.

> forcedeth 0000:00:07.0: ifname eth0, PHY OUI 0x50ef @ 0, addr
> 00:22:68:72:e6:a1

> ============================

> forcedeth 0000:00:07.0: ifname eth0, PHY OUI 0x50ef @ 0, addr
> 00:22:68:72:e6:a1
> forcedeth 0000:00:07.0: highdma pwrctl mgmt lnktim msi desc-v3

> cdc_ether 2-7:1.1: eth1: register 'cdc_ether' at usb-0000:00:02.0-7, CDC
> Ethernet Device, 00:40:7b:71:9b:f3


It would have been easier if you trimmed the obvious non-network stuff.

What is the output of lspci|grep Ethernet

Also what are the contents of /etc/udev/rules.d/70-persistent-net.rules?

I'm not sure why you want to have two connections?  Is this a router? 
Are either of the connection drivers built as a module?

I would think that a network interface based on usb is a bit 
problematical.  There would need to be some kind of script run to 
configure the interface at any connection/disconnection.

   -- Bruce




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