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Netboot

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Revision as of 12:32, 30 January 2022 by Adamplumb (talk | contribs) (Usage: Switched flasher command to say boot so it prevents destructive writes.)
Warning WARNING: Netboot support is not yet merged into pmbootstrap & pmaports

Netboot describes the means of booting a device when the rootfs is not on the device but accessed via network, in this implementation via USB networking.

Preparations

Make sure your kernel has the necessary kernel config options for netboot.

$ pmbootstrap kconfig check --netboot $kernel-package-name

If not you need to adjust your kernel config otherwise netboot won't work.

Usage

First prepare a rootfs for your device. It is advisable to use the --extra-space argument to increase the size of your rootfs (in the example you will get 1000MB of extra space) as no image resize will happen at runtime.

$ pmbootstrap --extra-space 1000 install

Then prepare your boot.img and flash it to the device:

$ pmbootstrap initfs hook_add netboot
$ pmbootstrap flasher boot # or however you flash/boot the kernel

After booting the device a network interface should appear over USB networking.

Finally you need to start the netboot server on your computer with the following command:

$ pmbootstrap netboot serve

Make sure to open up tcp port 9999 on your computer's firewall so the phone can connect to your netboot service.

If you've never used netboot for the current device, then the image from the previous pmbootstrap install will get copied to $pmbootstrap_work/images_netboot/ and will persist normal pmbootstrap zap calls as you will probably have data in your rootfs.

Note: For android devices, you may need to run fastboot erase dtbo before flashing/booting the kernel. If you are running an a/b slot device, make sure to add the correct suffix (dtbo_a or dtbo_b).

Replacing persisted rootfs

You can replace the persisted rootfs image with a fresh image from pmbootstrap install:

$ pmbootstrap netboot serve --replace

Deleting all netboot images

You can delete all persisted rootfs images:

$ pmbootstrap zap --netboot

See also