PiBox

See piboxd:eth.c

#define ETH0_STATE_PATH   "/sys/class/net/eth0/carrier"

If this is 1 then we can enable dhcp. At least until we put network startup in the background.

This isn't what I expected. The use of Busybox's ifup places starting of dhcp inside the ifup binary embedded in Busybox. So I can't actually check there for the eth port connection.

What I can do is change S40network to not use ifup -a, but rather ifup <interface> and iterate across all interfaces one at a time. It will look something like this.

#!/bin/sh

myfunc()
{
    for ifacep in /sys/class/net/*
    do
        iface="$(basename ${ifacep})" 
        if [ "${iface}" == "lo" ]
        then
            continue
        fi
        if [ ! -e "${ifacep}/wireless" ]
        then
            echo "${iface} is not wireless" 
            carrier=$(cat ${ifacep}/carrier)
            if [ ${carrier} -eq 1 ]
            then
                echo "Do ifup ${iface}" 
            fi
        fi
    done
}

( myfunc ) &

Running the function inside () places it in a subshell, which we then background. This is equivalent of the double fork for a daemon process in C. This allows the S40network script to complete even though network startup is in progress, thus speeding up initial bootup.

It's unclear at this point if any system apps will puke because networking is not up yet. An alternative is to only place each instance of ifup <iface> in the double fork though I'm not sure that will help if some app requires networking to be up before it starts. Given that only piboxd will run at boot time (and launcher) on system builds I don't think this will be much of an issue.