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Diffstat (limited to 'meta-netboot/README')
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diff --git a/meta-netboot/README b/meta-netboot/README new file mode 100644 index 000000000..130477751 --- /dev/null +++ b/meta-netboot/README @@ -0,0 +1,64 @@ +meta-netboot +============ + +This layer contains some recipes and configuration adjustments to allow network boot through NBD (network block device). + +Content and usage +----------------- + +This layer creates a new supplementary initrd image which can be downloaded through TFTP with the kernel. +At boot time, the init script will try to mount the rootfs based on the following kernel command line parameters: +* nbd.server: IP address to reach the NBD server +* nbd.port: TCP port on which server is listening (default: 10809) +* nbd.dev: nbd device to use (default: /dev/nbd0) +* nbd.debug: activate debug mode (init script is then interruptible) + +The layer meta-netboot contains recipes for the following components: +* busybox: activate the built-in NBD client +* initramfs-netboot: contains the init script started by the kernel: basically, this script mounts the real root filesystem, then pivot_root on it and finally exec systemd. +* initramfs-netboot-image: image to specify for building the initrd + +To enable the build of the netboot initrd and ext4 rootfs, add the following line in conf/local.conf: + +INHERIT += "netboot" + + +Server side +----------- + +On the server side (assuming that the build dir is stored in $BUILD) we can run: + +* a TFTP server, for example tftpd-hpa started with $BUILD/tmp/deploy/images as the TFTP dir: + + /usr/sbin/in.tftpd --listen --user tftp --address 0.0.0.0:69 --secure $BUILD/tmp/deploy/images + +* a NBD server, for example xnbd-server, used to expose the whole ext4 rootfs as a network block device: + + xnbd-server --target --lport 10809 $BUILD/tmp/deploy/images/$MACHINE/agl-demo-platform-$MACHINE.ext4 + + +Target side +----------- + +On the target board, a specific setup should also be done. For example, for Renesas Porter board, the following U-boot environment could be used (adjust IP addresses !): + +------------------------------------------------------------------ +setenv 'bootkfile' 'uImage+dtb' +setenv 'bootkaddr' '0x40007fc0' +setenv 'bootifile' 'initramfs-netboot-image-porter.ext4.gz.u-boot' +setenv 'bootiaddr' '0x50000000' +setenv 'ipaddr' '<board_IP>' +setenv 'serverip' '<server_IP>' + +setenv 'bootargs_console' 'console=ttySC6,38400 ignore_loglevel' +setenv 'bootargs_video' 'vmalloc=384M video=HDMI-A-1:1280x960-32@60' +setenv 'bootargs_extra' 'rw rootfstype=ext4 rootwait rootdelay=2' +setenv 'bootargs_root' 'root=/dev/ram0 ramdisk_size=16384 ip=dhcp' +setenv 'bootkload_net' 'tftp ${bootkaddr} porter/${bootkfile}' +setenv 'bootiload_net' 'tftp ${bootiaddr} porter/${bootifile}' +setenv 'bootcmd' 'setenv bootargs ${bootargs_console} ${bootargs_video} ${bootargs_root} ${bootargs_extra} nbd.server=${serverip}; run bootkload_net; run bootiload_net; bootm ${bootkaddr} ${bootiaddr}' + +saveenv # optional: saves env in flash +run bootcmd # boots the board, executed automatically after power up +------------------------------------------------------------------ + |