Hello, I'm running Gentoo x86/2006.1 inside a User-Mode Linux disk image, created according to the instructions at http://gentoo-wiki.com/HOWTO_User_Mode_Linux, with kernel 2.6.20.7 from kernel.org. The first time I booted my UML system, networking worked properly. The next time, net.eth0 failed to start. Further investigation revealed that /sys/class/net/eth0 didn't exist (despite entries in dmesg indicating that it was being created). However, /sys/class/net/eth1 *did* exist, despite me not having specified a configuration for eth1 on the UML command line. I was able to successfully configure eth1 and communicate with other hosts through it.
The next time I rebooted, eth1 had dissappeared, but there was now an eth2. dmesg still contained references to /sys/class/net/eth0, but nothing about eth2. The next time, I got eth3. And so on. I rebuilt my UML image from scratch, and got eth0 again on the first boot, but the device number kept incrementing on further reboots. I rebuilt the kernel with a few different options, but that didn't affect the numbering. I'm at eth12 now. I have an older UML image based on kernel 2.6.16.16 and Gentoo 2006.0 from last June or so; it doesn't display this behaviour. I've double-checked that all UML-related processes have shut down completely between reboots, and have deleted and re-created the tun/tap device on the host system to ensure that the issue isn't with the host operating system. The UML command line didn't change between boots. Since the problem is persistent across UML reboots, and changing the kernel didn't help, I'm convinced that the issue lies with the Gentoo operating system in the UML image. Unfortunately, I have no idea what the problem is. Does anyone have any idea what might be going on? Any help would be greatly appreciated. Rennie deGraaf