RE: Problems switching from busybox-udhcpc to dhcpcd

[Bryan Evenson <bevenson@melinkcorp.com>]

All,

I solved my problems.

> -----Original Message-----
> From: yocto@lists.yoctoproject.org <yocto@lists.yoctoproject.org> On
> Behalf Of Bryan Evenson via lists.yoctoproject.org
> Sent: Thursday, January 6, 2022 9:32 AM
> To: yocto@lists.yoctoproject.org
> Subject: [yocto] Problems switching from busybox-udhcpc to dhcpcd
> 
> I have a system that is based off core-image-minimal which uses sysvinit and
> busybox-udhcpc.  I'm trying to switch to dhcpcd because I want to get the
> NTP server list from the local DHCP server; dhcpcd supports this feature and
> busybox-udhcpc does not.  I'm on the dunfell branch.  I think I finally got
> firmware upgrade to work cleanly (with opkg) but I'm having trouble
> triggering dhcpcd.  It doesn't work straight out of the box and I'm looking for
> assistance in how to get dhcpcd started.
> 
> First, here are the recipe changes I made in my custom layer to install dhcpcd
> onto my image and for it to get pulled in on firmware upgrade.
> 1. I added the following to my busybox_%.bbappend:
> 
> Do not install busybox-udcpcd, since we are using dhcpcd
> RRECOMMENDS_${PN} = ""
> 
> 2. I modified my busybox defconfig to unset all the udhcpc related
> configuration features
> 
> 3. I created a dhcpcd_%.bbappend with these contents:
> # Set the package to conflict with busybox-udhcpc
> RCONFLICTS_${PN} = "busybox-udhcpc"
> RREPLACES_${PN} = "busybox-udhcpc"
> 
> # Add configuration settings to enable NTP configuration
> PACKAGECONFIG += " \
>                    ntp \
>                  "
> PACKAGECONFIG[ntp] = "--with-hook=ntp, , , ntp"
> 
> # Include the hook scripts on the system
> EXTRA_OECONF += " \
>                  --with-hooks \
>                 "
> 4. In my init-ifupdown_%.bbappend:
> 	a. I added dhcpcd to the RDEPENDS list
> 	b. I added a script to start dhcpcd and installed it in the
> ${D}${sysconfdir}/network/if-up directory
> 
> 5. Here is the if-up script (note: I only have one Ethernet port on this device
> which will always be eth0):
> #!/bin/sh
> 
> # Only do this for eth0 and not the loopback interface
> if [ "$IFACE" == "eth0" ]; then
>   # Start the DHCP client
>   dhcpcd -4 -6 -f /etc/dhcpcd.conf "$IFACE"
> fi
> 
> 
> I think I'm close, but the dhcpcd never gets called when the Ethernet
> interface starts up.  As best I can tell from my debugging, I think $IFACE is
> never set whenever my if-up script is called.  I'm not sure why that is,
> because I have a pre-up script that depends on $IFACE that has been working
> for years for me.

First, I was having issue even directly calling dhcpcd from the command line with the line I had in my pre-up script.  There have been some updates to the dhcpcd recipe in master that affects the file installation locations.  I copied the dhcpcd recipe in master and put it in my custom layer.  I could then call dhcpcd directly without issue.

Second, I needed to enable the CONFIG_FEATURE_IFUPDOWN_EXTERNAL_DHCP configuration parameter in busybox.  The ifup and ifdown applets from Busybox were not attempted to call dhcpcd without this set.  Once I got both of these fixes in place, I found out that I don't need the if-up script I had created.  Everything is running fine now.

> 
> Has anyone else made this transition that can offer some more support?  Are
> there some examples floating around on how to start dhcpcd on ifup that I
> am missing?
> 
> Thanks,
> Bryan Evenson

Bryan Evenson