I was asked to share details about my root-over-NFS setup so here they are. I decided to split how-to in two posts: server/kernel part and u-boot part.
Usual components in the setup are:
- DHCP server
- TFTP server
- NFS server
- NAT (optional)
DHCP server
I use net/isc-dhcp42-server as a server. Sample dhcpd.conf:
option root-opts code 130 = string; # NFS / mount options
log-facility local7;
subnet 192.168.10.0 netmask 255.255.255.0 {
server-name "cinderella.bluezbox.com";
server-identifier 192.168.10.1;
option subnet-mask 255.255.255.0;
option broadcast-address 192.168.10.255;
option domain-name-servers 8.8.8.8;
option domain-name "bluezbox.com";
next-server 192.168.10.1;
option routers 192.168.10.1;
}
group {
host pandaboard {
hardware ethernet 0E:60:33:B1:46:01;
fixed-address 192.168.10.90;
filename "kernel.PANDA.bin";
option root-path "/src/FreeBSD/nfs/armv6";
option root-opts "nolockd";
}
host rpi {
hardware ethernet b8:27:eb:f6:08:83;
fixed-address 192.168.10.91;
filename "ubldr";
option root-path "/src/FreeBSD/nfs/rpi";
option root-opts "nolockd";
}
}
Config is pretty self-explanatory. I use google’s 8.8.8.8 nameserver but you can change it to your very own DNS server. Difference between various filename “…” will be explained later.
dhcpd should be enabled in rc.conf(5)
dhcpd_enable="YES"
TFTP server
TFTP server provides access to all files described in filename “…” options so it’s better to keep them together. By default it’s /tftpboot directory but I have whole drive dedicated to FreeBSD development environment and mounted under /src/FreeBSD mountpoint. So I keep everything there and my TFTP server root is /src/FreeBSD/tftpboot. TFTP server is standard FreeBSD’s one and config line in inetd.conf(8) looks like:
tftp dgram udp wait root /usr/libexec/tftpd tftpd -l -s /src/FreeBSD/tftpboot
inted should be enabled in rc.conf(5)
inetd_enable="YES"
NFS Server
NFS server is not just one daemon but several services combined. So rc.conf(5) part of config looks like this:
rpcbind_enable="YES"
rpc_statd_enable="YES"
rpc_lockd_enable="YES"
nfs_server_enable="YES"
mountd_enable="YES"
Filesystems that are exported via NFS listed in exports(5). Mine contains following:
# Mind mount points obj and nfs are different
/usr/ports -maproot=0 -network 192.168.10.0/16
/src/FreeBSD/head /src/FreeBSD/nfs/rpi /src/FreeBSD/nfs/armv6 /src/FreeBSD/nfs/am335x -maproot=0 -network 192.168.10.0/16
Note that you can join several directories into one line only if they belong to the same mount point.
NAT
If you’re planning on building ports on the device – you’ll need internet access on it. All my devices are restricted to one LAN with laptop acting as a gateway. I use pf(4) for NATing. Config:
/etc/pf.conf(5)
ext_if=em0
rede="{192.168.0.0/16}"
nat on $ext_if from $rede to any -> ($ext_if)
and rc.conf(5)
gateway_enable="YES"
pf_enable="YES"
pf_rules="/etc/pf.conf"
pf_flags=""
Kernel config
FreeBSD kernel should be properly configured in order to be suitable for mounting root over NFS:
options NFSCL
options NFSCLIENT # NFS v3
options NFS_ROOT
options BOOTP_NFSROOT
options BOOTP_COMPAT
options BOOTP
options BOOTP_NFSV3
options BOOTP_WIRED_TO=ue0
BOOTP_WIRED_TO value is SoC-specific. If you do not have full control over your DHCP server (e.g. it’s cable modem) and can’t specify root-path/root-opts you still can hardcode root location by removing BOOTP_NFSROOT and adding
options ROOTDEVNAME=\"nfs:192.168.10:/src/FreeBSD/nfs/rpi\"
Installation
Depending on your boot sequence installation consists of one or two steps.
Normal system installation, e.g.:
sudo -E make TARGET_ARCH=armv6 DESTDIR=/src/FreeBSD/nfs/rpi -DDB_FROM_SRC installworld
sudo -E make TARGET_ARCH=armv6 DESTDIR=/src/FreeBSD/nfs/rpi -DDB_FROM_SRC distribution
And installing kernel copying kernel to tftpboot directory:
sudo -E make TARGET_ARCH=armv6 DESTDIR=/src/FreeBSD/nfs/rpi -DDB_FROM_SRC installkernel
cp /src/FreeBSD/nfs/rpi/boot/kernel/kernel /src/FreeBSD/tftpboot/kernel.RPI
In some cases you’d want to use kernel.bin instead of kernel (more on it in next post) so second step would look like
sudo -E make TARGET_ARCH=armv6 DESTDIR=/src/FreeBSD/nfs/rpi -DDB_FROM_SRC KERNEL_EXTRA_INSTALL=kernel.bin installkernel
cp /src/FreeBSD/nfs/rpi/boot/kernel/kernel.bin /src/FreeBSD/tftpboot/kernel.RPI.bin
And if you’re going to use ubldr, there is no need to copy installed kernel anywhere.
More details on different types of binaries and boot process in the next post
