[uml-devel] [BUG!?] Re: [uml-user] TUNSETIFF failed, errno = 16SIOCSIFFLAGS: Device or resource busy

[uml-devel] [BUG!?] Re: [uml-user] TUNSETIFF failed, errno = 16SIOCSIFFLAGS: Device or resource busy

[roland]

hi!

> > When I start up my UML, the networking works fine.  If I bring down my
> > interface and attempt to bring it back up again, I get the following
> > message.
> >
> > # ifconfig eth0 down
> > # ifconfig eth0 up
> > TUNSETIFF failed, errno = 16SIOCSIFFLAGS: Device or resource busy

> ... which it is: it's a component of the bridge, and doesn't have its
> own independent existence anymore.

yes - and that is why we should somewhat call it a "bug" - because a uml user indeed is allowed to bring down/up eth0, but he
(usually) isn't allowed to do something outside the uml.

so - what could he do?
call his uml provider to tell him he should fix the tun/tap/bridge for him?

no - uml should handle this itself,IMHO.

> Either bring down br0, or bring down the UML side of the link.
that is a workaround , not a solution.
i think UML needs some fix to handle tun/tap via bridge appropriately.

regards
roland






----- Original Message ----- 
From: "Nix" <nix@esperi.org.uk>
To: "Naomi Fox" <schpoo@Dartmouth.EDU>
Cc: <user-mode-linux-user@lists.sourceforge.net>
Sent: Wednesday, June 16, 2004 5:52 PM
Subject: Re: [uml-user] TUNSETIFF failed, errno = 16SIOCSIFFLAGS: Device or resource busy


> On Tue, 15 Jun 2004, Naomi Fox stated:
> > I am running a uml using a tuntap device connected to a bridge.
> >
> > # brctl show
> > bridge name     bridge id               STP enabled     interfaces
> > br0             8000.000255ffc0ce       no              eth0
> >                                                         tap0
> >
> > When I start up my UML, the networking works fine.  If I bring down my
> > interface and attempt to bring it back up again, I get the following
> > message.
> >
> > # ifconfig eth0 down
> > # ifconfig eth0 up
> > TUNSETIFF failed, errno = 16SIOCSIFFLAGS: Device or resource busy
>
> ... which it is: it's a component of the bridge, and doesn't have its
> own independent existence anymore.
>
> Either bring down br0, or bring down the UML side of the link.
>
> Example, from my startup scripts, using the brctl and ip tools instead
> of ageing ifconfig:
>
> brctl addbr adsl
> brctl stp adsl off
> brctl setfd adsl 1
> brctl sethello adsl 1
>
> brctl addif adsl adsl-phys
> brctl addif adsl tap0
>
> ip link set dev adsl mtu 1458 up
>
> -- 
> `We in no way believe that this Christ was a space alien.'
>                     --- A creationist website goes completely bonkers
>
>
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[uml-devel] Re: [BUG!?] Re: [uml-user] TUNSETIFF failed, errno = 16SIOCSIFFLAGS: Device or resource busy

[Nix]

On Wed, 16 Jun 2004, roland stipulated:
> hi!
> 
>> > When I start up my UML, the networking works fine.  If I bring down my
>> > interface and attempt to bring it back up again, I get the following
>> > message.
>> >
>> > # ifconfig eth0 down
>> > # ifconfig eth0 up
>> > TUNSETIFF failed, errno = 16SIOCSIFFLAGS: Device or resource busy
> 
>> ... which it is: it's a component of the bridge, and doesn't have its
>> own independent existence anymore.
> 
> yes - and that is why we should somewhat call it a "bug" - because a
> uml user indeed is allowed to bring down/up eth0, but he (usually)
> isn't allowed to do something outside the uml.

This is just the analogue of the way in which taking a link down from
one end will automatically take it down at the other end, too.

>> Either bring down br0, or bring down the UML side of the link.
>> that is a workaround , not a solution.
> i think UML needs some fix to handle tun/tap via bridge appropriately.

Er, it works now. :)

-- 
`We in no way believe that this Christ was a space alien.'
                    --- A creationist website goes completely bonkers


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