[Bridge][Xen-devel] nfsroot and brige [fwd]

[Adam Sulmicki <adam@xxxxxxxxxxxx>]

On Wed, 12 Jan 2005, Ian Pratt wrote:

> It really bugs me that there's no atomic way to configure a bridge and
> transfer an IP address already active on another interface to it. I'm
> not 100% convinced that the current behaviour is actually what the
> bridge code author's intend: a the host can still transmit packet's with
> an IP associated with an eth interface that is part of a bridge, it just
> can't receive packets on that IP. I'd certainly appreciate it if someone
> could ask the question on the bridge mailing list...
FYI, this is what i got from the list.

it does mention the 2nd idea I was toying with though. static version of 
ifconfig and brctlr and put them into tmpfs /tmp filesystem.
---------- Forwarded message ----------
Date: Thu, 13 Jan 2005 11:17:33 -0800
From: Stephen Hemminger <shemminger@xxxxxxxx>
To: Adam Sulmicki <adam@xxxxxxxxxxxx>
Cc: Bridge mailing list <bridge@xxxxxxxx>
Subject: Re: [Bridge] RE: [Xen-devel] nfsroot and brige (fwd)

On Wed, 12 Jan 2005 16:40:25 -0500 (EST)
Adam Sulmicki <adam@xxxxxxxxxxxx> wrote:

> any comments?
>
> if nothing else, is there any way to atomically setup bridge?
>
> not on list, please cc.
>
> ---------- Forwarded message ----------
> Date: Wed, 12 Jan 2005 21:08:15 -0000
> From: Ian Pratt <m+Ian.Pratt@xxxxxxxxxxxx>
> To: Adam Sulmicki <adam@xxxxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxxx
> Subject: RE: [Xen-devel] nfsroot and brige
>
> > hello,
> >         it seems like a catch-22 to me. I boot xen0 with nfsroot,
> >         and then try to setup bridge stuff. something like this
> >
> > /sbin/brctl addbr xen-br0
> > /sbin/brctl addif xen-br0 eth0
> > /sbin/ifconfig xen-br0 10.0.10.103 netmask 255.255.255.0 up
> > /sbin/ifconfig eth0 0.0.0.0 promisc up
> >
> >         however, once I start it running it crashes down with error
> >         that nfs server is not available.
> >
> >         does it mean that I must use initramfs to configure bridge
> >         first, or is there some other way?
> It really bugs me that there's no atomic way to configure a bridge and
> transfer an IP address already active on another interface to it. I'm
> not 100% convinced that the current behaviour is actually what the
> bridge code author's intend: a the host can still transmit packet's with
> an IP associated with an eth interface that is part of a bridge, it just
> can't receive packets on that IP. I'd certainly appreciate it if someone
> could ask the question on the bridge mailing list...
>
> The workarounds for using nfsroot in dom0 at the moment are: a) use a
> ramfs to configure the bridge; b) use a routed rather than bridged
> setup.
>
> I'm actually going off the whole idea of bridging rather than routeing
> as the default...
>
> Ian

It wouldn't be that hard to write a small command that does the ioctl's
you need to setup the bridge and ip addresses at one time.  To just
create a bridge, add interface and move the IP address would be relatively
easy.

Or just put brctl and ifconfig in a ram filesystem (like initrd).

--
Stephen Hemminger       <shemminger@xxxxxxxx>


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