regression: console output on AWS arm instance no longer works on >= Jammy

[Thomas Bechtold]

[Impact]
The console output on AWS ARM instances does no longer work.
Steps to reproduce (with a noble daily image in eu-central-1):

1) $ aws ec2 run-instances --image-id ami-0baabea5d9d1fcd47 --instance-type c6g.large --key-name toabctl
2) $ aws ec2 get-console-output --instance-id i-0e21f778ac54c489d
{
    "InstanceId": "i-0e21f778ac54c489d",
    "Timestamp": "2024-01-23T08:49:31+00:00"
}

The expected output from command 2) is the console log.

The reason why this doesn't work is a fix for LP:#2036730 in livecd-rootfs (see commit https://git.launchpad.net/livecd-rootfs/commit/live-build/ubuntu-cpc/hooks.d?id=21321ac018d3771c7536a4cd1295e7eabfc5de54 ). On AWS, the console needs to be ttyS0 .

[Test plan]
1) build EC2 image with the proposed fix
2) boot an instance with the built image
3) run "aws ec2 get-console-output --instance-id XXX" and verify that the console output is there

[Thomas Bechtold (toabctl)]

Images with serial 20240124 solve this problem. Please reopen if you still see this problem.