Comment 3 for bug 1900695

Hi, I am seeing the same issue on MAAS + HPE Synergy Gen 10.

I can see Michal found a solution for his issue. I will leave what I've tested for the discussion.

It sets BIOS as the second viable option by the end of curtin.
Looking at the code we generally run with Bionic version, I can see there is not much logic on it to customize boot order:
https://git.launchpad.net/curtin/tree/curtin/commands/curthooks.py?h=ubuntu/bionic&id=a1d98115e5dc2b525a3f7556f4f97dd48693f608

However, on newer 20.2, there is an extra option: https://github.com/canonical/curtin/blob/81144052c64a3d22edb68ebbd11483b463e62656/curtin/commands/curthooks.py#L520
reorder_uefi_force_fallback

In my case, after setting that, I can see the boot order got rearranged on curtin logs:
Before: https://pastebin.canonical.com/p/mMp7BvbRWG/
After: https://pastebin.canonical.com/p/FCCQtxQH29/

For that, first I had to upgrade current curtin (on each infra node):
sudo add-apt-repository ppa:curtin-dev/stable
sudo apt update
sudo apt install --only-upgrade curtin-common

Then I had to add the fallback option to the /etc/maas/preseeds/curtin_userdata
reorder_uefi_force_fallback: True

According to the docs: https://curtin.readthedocs.io/en/latest/topics/config.html

I believe we should leave this option as True on preseed.