Messages in this thread | | | Date | Sat, 26 Jan 2013 11:29:49 +0100 | From | Toralf Förster <> | Subject | How to find an unused TAP device with kernel 3.8 ? |
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With kernel 3.8. I just realized that all pre-defined TAP devices are RUNNING even if no virtual linux system is using it. Now I'm wondering whether this is a new feature of the upcoming kernel, a bug of the old - and how I can avoid that.
Background : When I start a user mode linux instance, I currently grep for the next free tap device in this way :
Code: for t in $(ifconfig | grep "^tap" | cut -f1 -d:) do ethtool $t | grep -q 'Link detected: no' if [[ $? -eq 0 ]]; then NET="tuntap,$t" break fi done
but this doesn't work now anymore.
Here is the diff in dmesg
$ diff 3.7.1 3.8.0-rc1+ | grep UP
< br0: flags=4355<UP,BROADCAST,PROMISC,MULTICAST> mtu 1500 > br0: flags=4419<UP,BROADCAST,RUNNING,PROMISC,MULTICAST> mtu 1500
< tap0: flags=4099<UP,BROADCAST,MULTICAST> mtu 1500 > tap0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
more details : http://forums.gentoo.org/viewtopic-p-7211498.html#7211498
-- MfG/Sincerely Toralf Förster pgp finger print: 7B1A 07F4 EC82 0F90 D4C2 8936 872A E508 7DB6 9DA3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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