Re: [PATCH v2] allow ifup bring up network manually even without netroot

[Cong Wang <xiyou.wangcong-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

On Fri, 30 Dec 2011 at 08:38 GMT, Dave Young <dyoung-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> wrote:
> For kdump we need scp vmcore to remote machine, the nic to be used is
> not limited to netroot one. we need a feature for manually bringing up
>  network interface. Also it is useful for emergency shell with
> ssh-client for recovery or test purpose
>
> I implement this by adding one argument to ifup script, user can use
> `/sbin/ifup eth0 -m` to bring up eth0, note ifup will regard it a
> manual operation for the nic specified in 1st argument if there's
> the 2nd argument.
>
> If same nic is used for netroot the 2nd argument will be ignored,
> in this case we will leave netroot bring up it automatically to
> avoid side effect. And in this case hooks such as kdump will need to
> execute after netroot mounted.
>
> `ifup eth0 -m` will create /tmp/net.eth0.manualup stamp file,
> later dhclient-script can check this and pass $2 to netroot,
> then netroot script will bring eth0 up
>

As we talked on IRC, we still need to discuss if this is really
needed, from kdump perspective. If we need to invoke `ifup` by
ourselves, then we also need to determine which NIC we should bring
up, this will make kdump code larger.

So, I hope, we can have some kernel cmdline (like ip=...) to tell
dracut which NIC we want to bring up in the second kernel, provided by
either ssh-client module or nfs module.

Let's see what Harald thinks...