Kontron AM4220 User Manual

Page 78

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• Copy the kernel built in step 1 into the tftpboot directory of the development host. E.g. the kernel for

the WindRiver Linux BSP is located in the build/export directory of the WindRiver Linux BSP
(kontron_t5516-vmlinux-stripped-WR2.0ap_standard).

• Copy the root file system built in step 1 into the NFS exported file tree. E.g. the root file system for the

WindRiver Linux BSP is located in the build/export/dist directory of the WindRiver Linux BSP. In the
following, it is assumed that the root filesystem has been copied into /export/T5516/nfsroot on the
development host.

• Reset the AM4220 and enter the bootloader CLI using the bootstop phrase ‘stop’

• Setup the bootloader environment variables for booting a NFS root filesystem.

Kontron T5516#

setenv rootpath ’/export/T5516/nfsroot’

Kontron T5516#

setenv bootargsnfs ’setenv bootargs root=/dev/nfs rw nfsroot=${serverip}:${rootpath} ip=${ipad-

dr}:${serverip}:${gatewayip}:${netmask}:${hostname}::off’

Kontron T5516#

setenv bootcmdnfs ’run bootargsnfs ; bootp && tftpboot ${loadaddr} ${bootfile} && bootoctlinux

${loadaddr} numcores=${linuxcores} mem=${linuxmem} console=ttyS0,${baudrate}n8r ${mtdparts} ${bootargs}’

Kontron T5516#

setenv bootfile t5516-vmlinux-stripped-WR2.0ap_standard

Kontron T5516#

save

• Boot the Linux kernel from the bootloader CLI

Kontron T5516#

run bootcmdnfs

The kernel is loaded via tftp and mounts its root filesystem via NFS. Note that the standard kernel delivered
by Kontron mounts an overlay JFFS2 file system located in the mtd4 flash partition to /. All files available on
the NFS server are still available on the AM4220 system. However, if a file is changed from the target, the
changes are stored in the local JFFS2 partition and cannot be seen from the development host. This allows
providing one single root filesystem exported via NFS on the development host for several AM4220 target
boards. Changes for a specific target system are stored only on the targets JFFS2 partition and apply not for
other targets. This allows to setup different targets in a different way without the need to provide more root
filesystem trees on the development host.