[patch] tun(4) and tap(4) if_clone support.

[Landon Fuller]

On Nov 8, 2006, at 06:33, Bruce M. Simpson wrote:

> Landon Fuller wrote:
>> Nick Barkas (snb at threerings.net) and I have added interface  
>> cloning support to the tun(4) and tap(4) drivers.
>>
>> We maintained backwards-compatible support for devfs cloning,  
>> which is now disabled by default -- it can be re-enabled via a  
>> sysctl. Interfaces that are created via devfs cloning may still be  
>> removed via ifconfig destroy.
>>
>> The latest patch is available here
>>     http://www.opendarwin.org/~landonf/code/patch-tuntap_ifclone
>>
>> I've submitted kern/105228 with the patch, and I'd be most  
>> appreciative of comments/suggestions.
>
> Interesting stuff. If it eliminates a race on creation, that has to  
> be a good thing; I may have run into this race in the past month or  
> two. It would however change tap/tun behaviour in that currently I  
> have a few scripts which use dd(1) to force the device node to be  
> created. This is undocumented behaviour specific to its devfs  
> implementation which perhaps I shouldn't be relying upon, before I  
> go on to create a bridge from several tap instances (which are then  
> hooked up to QEMU virtual machines).

I disabled the devfs support by default with deprecation in mind, but  
there's no other reason it couldn't be default-enabled. What's the  
race you've run into?

> Good work!

Cheers!

-landonf

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