Appendices : Advanced Boot and Backup Configuration : U-Boot network boot options and caveats

U-Boot network boot options and caveats
When a network boot is performed with the U-boot net_boot command, the OnBoard appliance boots from the specified image on the TFTP server. The image uses the RAM as the root file system. Network boots are useful for troubleshooting because the net-booted image can run even if there the OnBoard appliance’s Flash memory is not usable.
Network boots are recommended only for troubleshooting and must not be used for normal operation of the OnBoard appliance. For example, if you want to test a new release of the software to make sure a problem is fixed, or if the removable Flash memory becomes corrupted, you could download the software to a tftpboot server and then save it to the removable Flash after testing, using the create_cf command with the appropriate options (see Options for the create_cf command).
When a network boot is performed, the system uses one of the two following sources of configuration data:
Any configuration changes made after the last backup copy was made are lost unless the configuration files were backed up before the network boot and then restored afterwards (see Backing Up Configuration Files and Restoring Backed Up Configuration Files).
To upgrade to a boot image from a network boot in U-boot monitor mode:
Before performing this procedure, make sure that a copy of the latest boot image has been downloaded from the Cyclades ftp site (ftp.cyclades.com/pub/cyclades/alterpath/onboard/released) to a TFTP server that is accessible to the OnBoard appliance.
1.
If needed, see To use the onbdtemplate utility to test a template:.
2.
Set the bootfile, serverip, and ipaddr environment variables using the boot filename, the TFTP boot server’s IP address, and the IP address of the OnBoard appliance to use for network booting.
The format of the boot filename is: zImage_onb_version_number.bin. In the following example, the filename zImage_onb_v120.bin is used.
See the following screen example.
 
3.
4.
5.
6.
The following command example shows using the --factory_default argument to restore the factory default configuration files at the same time.
CAUTION:Be aware that the --doformat option erases the Flash memory and installs the boot image into the image1 area. See Options for the create_cf command for other options.
7.
8.
See To use the onbdtemplate utility to test a template:, if needed.
9.