How can I modify any of the Ubuntu images and make it boot from a USB device on a computer with UEFI?
I'm looking to modify either the 16.04 desktop image, 16.04 server image or an alternate version of 16.04.
I would like to be able to make changes to grub.cfg on the iso to add a ks file over network.
I have tried doing this in multiple different ways, but I seem to end up with an image that when DDed to a USB device (or by using Startup Disk Creator) won't boot automatically. I can manually choose an EFI file and start it by selecting the correct one on the USB - but I would like for it to work by itself.
I have tried unpacking the image, changing the one file and packing it again - but this results in an image that doesn't boot from USB. I have tried changing a single file in the image with 'ISO Master' - same result.
I'm unable to understand why changing a single file results in the image not being able to boot and any help would be appreciated.