Factory reset GRUB config (99_reset) does not boot to the installer

[Yao Wei]

In subiquity/server/controllers/install.py, it creates 99_reset for GRUB config if factory-reset is set:

#!/bin/sh
{HEADER}

set -e

cat << EOF
menuentry "Restore Ubuntu to factory state" {{
      search --no-floppy --hint '(hd0,{PARTITION})' --set --fs-uuid {FS_UUID}
      linux /casper/vmlinuz uuid={CASPER_UUID} rp-partuuid={RP_UUID} nopersistent
      initrd /casper/initrd
}}
EOF

However, this boot entry cannot boot into the factory reset mode for the following reasons:
1. This does not boot into live squashfs layer, that means it boots into the "installed" live environment.
2. We would like to configure the boot parameters so we could specify cloud-configs to be used, and disable nouveau during and after installation.

This is the GRUB config we are using for the reset partition, for example:

menuentry "Restore Ubuntu to factory state" {
 set gfxpayload=keep
 linux /casper/vmlinuz layerfs-path=minimal.standard.live.squashfs nopersistent ds=nocloud\;s=/cdrom/cloud-configs/reset-partition --- quiet splash modprobe.blacklist=nouveau nouveau.modeset=0
 initrd /casper/initrd
}

[Yao Wei (medicalwei)]

My proposal is not to load Linux kernel, but maybe chainload into /EFI/boot/bootx64.efi so that we can use the GRUB option over there.

Do you think this is okay?

[Yao Wei (medicalwei)]

GitHub PR: https://github.com/canonical/subiquity/pull/1894

[Michael Hudson-Doyle (mwhudson)]

We shouldn't need layerfs-path=minimal.standard.live.squashfs on the kernel command line any more since recent changes to livecd-rootfs to set this in the initrd for desktop ISOs. But the other stuff makes sense.