110 • Step-by-Step Guide to your own Linux ApplicationFile System and Linux Kernel UpdateWAGO-I/O-SYSTEM 750Linux Fieldbus Coupler5.10 File System and Linux Kernel UpdateIf you do not want to update a single program but the entire file system or theLinux kernel, this is possible using TFTP. The make parameters romfs orimage create image files which are copied into the Linux coupler via TFTP.In order that the file system and the Linux kernel can be updated, the userneeds to have access rights for the /tftpboot output directory in the rootdirectory:> suPassword> mkdir /tftpboot> chmod 777 /tftpbootTo create new image files, use the following call:> cd ~/uclinux-dist> make romfs imageTo restore the Linux coupler default values, use the image files of the BordSpport Package (BSP).The image files jffs2.img and linux.flashme are created in the /tftpbootdirectory. The image files are transferred to the Linux fieldbus coupler viaTFTP. For that purpose, you have to set up and start a TFTP server, which has/tftpboot as a base directory, on the development computer. The boot loader(U-Boot) on the Linux coupler provides a TFTP client. It is controlled via aseparate console. To open the console, enter the password geheim during theLinux coupler start-up. The boot process is aborted and the Linux fieldbuscoupler opens the boot loader communication interface. You can use theupdate-kernel and update-rootfs macros for the update.
