Use TFTP/NFS Testing BBB Kernel
Nov 2, 2014
Technology
Prerequisite
You have a tftp server and NFS server configured, in my environment these 2 server runs on ArchLinux, ip address is 10.0.0.221, while BBB takes another ip address, for example, 10.0.0.16.
NFS Server Preparation
Create the nfs server’s rootfs for BBB Black ,and open all of the priviledges :
# pwd
/media/y/embedded/BBB/svnco/trunk/bin/omap
# mkdir /srv/nfs4/BBBrootfs
# tar xzvf openwrt-omap-Default-rootfs.tar.gz -C /srv/nfs4/BBBrootfs/
# chmod 777 -R /srv/nfs4/BBBrootfs/
Now you have the NFS Server available.
TFTP Server Preparation
Since we are using u-boot for booting, we need create uImage, but in OpenWRT, its default generated file is zImage, so we need use following command for generate our own uImage:
# mkimage -A arm -O linux -T kernel -C none -a 0x80008000 -e 0x80008000 -n "Linux" -d ./zImage ./uImage
Image Name: Linux
Created: Sun Nov 2 20:39:08 2014
Image Type: ARM Linux Kernel Image (uncompressed)
Data Size: 1710568 Bytes = 1670.48 kB = 1.63 MB
Load Address: 80008000
Entry Point: 80008000
Also we have to copy the dtd file into our tftp folder:
[root@TrustyArch omap]# pwd
/media/y/embedded/BBB/svnco/trunk/bin/omap
[root@TrustyArch omap]# cp dtbs/am335x-boneblack.dtb /srv/tftp/
Easy Making Script
Following script will easy your life:
$ cat ~/autobuildnfs.sh
# First copy the kernel and dtd files into the tftp server
echo "##### Start copy to /srv/tftp####"
cp /media/y/embedded/BBB/svnco/trunk/bin/omap/openwrt-omap-zImage /srv/tftp/
cp /media/y/embedded/BBB/svnco/trunk/bin/omap/dtbs/am335x-boneblack.dtb /srv/tftp/
echo "###############Finished Copy!!!###############"
# Generate the uImage in /srv/tftp folder
mkimage -A arm -O linux -T kernel -C none -a 0x80008000 -e 0x80008000 -n "Linux" -d /srv/tftp/openwrt-omap-zImage /srv/tftp/uImage
# Remove the BBBrootfs content, all of them should be deleted.
rm -rf /srv/nfs4/BBBrootfs/
mkdir -p /srv/nfs4/BBBrootfs
# Now extract the newly generatd rootfs into the /srv/nfs4/BBBrootfs
tar xzvf /media/y/embedded/BBB/svnco/trunk/bin/omap/openwrt-omap-Default-rootfs.tar.gz -C /srv/nfs4/BBBrootfs/
U-boot Configuration
CheetSheet
When system startup, click ‘enter’ for getting the u-boot prompt interface, then set following:
setenv ipaddr 10.0.0.16
setenv serverip 10.0.0.221
tftpboot ${fdtaddr} am335x-boneblack.dtb
tftpboot ${kloadaddr} uImage
setenv bootargs console=ttyO0,115200n8 root=/dev/nfs rw nfsroot=10.0.0.221:/srv/nfs4/BBBrootfs ip=10.0.0.16:::::eth0
bootm ${kloadaddr} - ${fdtaddr}
CheetSheet2
setenv ipaddr 192.168.1.16
setenv serverip 192.168.1.221
tftpboot ${fdtaddr} am335x-boneblack.dtb
tftpboot ${kloadaddr} uImage
# For NFS
setenv bootargs console=ttyO0,115200n8 root=/dev/nfs rw nfsroot=192.168.1.221:/srv/nfs4/BBBrootfs ip=192.168.1.16:::::eth0 rootpath=/etc/preinit
# NFS with 192.168.1.1
setenv bootargs console=ttyO0,115200n8 root=/dev/nfs rw nfsroot=192.168.1.221:/srv/nfs4/BBBrootfs ip=192.168.1.1:::::eth0 rootpath=/etc/preinit
# For SD-Card
setenv bootargs console=ttyO0,115200n8 root=/dev/mmcblk0p2 ro rootfstype=ext4 rootwait
bootm ${kloadaddr} - ${fdtaddr}
setting and testing the network
Set the ipaddr, and save it into the u-boot, next time you won’t set it again.
U-Boot# setenv ipaddr 10.0.0.16
U-Boot# printenv ipaddr
ipaddr=10.0.0.16
U-Boot# setenv serverip 10.0.0.221
U-Boot# ping 10.0.0.221
link up on port 0, speed 100, full duplex
Using cpsw device
host 10.0.0.221 is alive
U-Boot# saveenv
Load Files From TFTP
Use following commands for loading uImage and dtb files from 10.0.0.221:
U-Boot# tftpboot ${fdtaddr} am335x-boneblack.dtb
U-Boot# tftpboot ${kloadaddr} uImage
Set NFS Startup Parameter
Following will let the kernel startup from the nfs server.
setenv bootargs console=ttyO0,115200n8 root=/dev/nfs rw nfsroot=10.0.0.221:/srv/nfs4/BBBrootfs ip=10.0.0.16:::::eth0
Now startup:
bootm ${kloadaddr} - ${fdtaddr}
Start Debugging Under NFS
First we met following error:
[ 1.015532] List of all partitions:
[ 1.019292] No filesystem could mount root, tried:
[ 1.024439] Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,255)
This is because we don’t enable NFS and ROOT on NFS in kernel configuration.
File System -> Network File System -> NFS Client Support, etc, see following picture: