On Mon, Aug 1, 2011 at 3:04 PM, Grant <emailgr...@gmail.com> wrote: >>> My laptop's >>> r8169 eth0 appears under ifconfig even when there's no ethernet cable >>> attached. That's the expected behavior isn't it? >> >> Sure; ifconfig will even tell you if the link is up or down. Just >> because the link is down doesn't mean the interface isn't there. :) > > I see eth0 under ifconfig on my laptop but not on my desktop. > Strangely, on my desktop eth0 does appear under iwconfig (no wireless > extensions). dmesg pertaining to eth0 and r8169 looks normal. lspci > -v says: > > Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168B PCI > Express Gigabit Ethernet controller > ... > Kernel driver in use: r8169 > > But no eth0 under ifconfig.
Time to go for a walk in /sys, to find out more information. Check out /sys/bus/pci/devices Now, with lspci, a NIC will look something like this: 01:08.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL-8139/8139C/8139C+ (rev 10) If I look under /sys/bus/pci/devices, I'll see a corresponding directory (compare the first column from the lspci output): 0000:01:08.0 If I run 'ls' in that directory, I see: -rw-r--r-- 1 root root 4096 2011-08-01 15:19 broken_parity_status lrwxrwxrwx 1 root root 0 2011-08-01 15:19 bus -> ../../../../bus/pci -r--r--r-- 1 root root 4096 2011-08-01 15:11 class -rw-r--r-- 1 root root 256 2011-08-01 15:11 config -r--r--r-- 1 root root 4096 2011-08-01 15:11 device lrwxrwxrwx 1 root root 0 2011-08-01 15:11 driver -> ../../../../bus/pci/drivers/8139too -rw------- 1 root root 4096 2011-08-01 15:19 enable -r--r--r-- 1 root root 4096 2011-08-01 15:11 irq -r--r--r-- 1 root root 4096 2011-08-01 15:19 local_cpus -r--r--r-- 1 root root 4096 2011-08-01 15:19 modalias -rw-r--r-- 1 root root 4096 2011-08-01 15:19 msi_bus lrwxrwxrwx 1 root root 0 2011-08-01 15:19 net:eth2 -> ../../../../class/net/eth2 drwxr-xr-x 2 root root 0 2011-05-12 10:47 power -r--r--r-- 1 root root 4096 2011-08-01 15:11 resource -rw------- 1 root root 256 2011-08-01 15:19 resource0 -rw------- 1 root root 256 2011-08-01 15:19 resource1 lrwxrwxrwx 1 root root 0 2011-08-01 15:19 subsystem -> ../../../../bus/pci -r--r--r-- 1 root root 4096 2011-08-01 15:19 subsystem_device -r--r--r-- 1 root root 4096 2011-08-01 15:19 subsystem_vendor -rw-r--r-- 1 root root 4096 2011-08-01 15:19 uevent -r--r--r-- 1 root root 4096 2011-08-01 15:11 vendor So, you an see a file named 'net:eth2', so I expect it would show up as eth2, absent any udev renaming or aliasing rules. -- :wq
