Comment 7 for bug 1874453

To aid in debugging more, could anyone affected provide the following information:

1. relevant Vagrantfile info (are you doing any major customizations?)
2. vagrant version
3. virtualbox version
4. host OS
5. relevant hw specs (as hardware can affect boot times)
6. run the vagrant up commands as `time vagrant up`. If you have to pull the box new try to time the download so it doesn't affect the timings too much
7. vagrant ssh in and run the following:

* systemd-analyze
* cloud-init analyze show

Those will show more info about boot timings and cloud-init timings.

8. if possible, run with a serial console debug printed to file. you can do that by adding the following snippet to your Vagrantfile

  NOW = Time.now.strftime("%d.%m.%Y.%H:%M:%S")
  FILENAME = "serial-debug-%s.log" % NOW
  config.vm.provider "virtualbox" do |vb|
     vb.customize [ "modifyvm", :id, "--uart1", "0x3F8", "4" ]
     vb.customize [ "modifyvm", :id, "--uartmode1", "file",
     File.join(Dir.pwd, FILENAME) ]
  end

I have reproduced the double booting issue. However in testing, I'm not seeing extreme slow boots on focal. My testing is showing ~30s slower boot time compared to Bionic, which is in line with seeing a kernel panic and reboot. All tests used the same basic Vagrantfile, only setting teh box and adding the debug serial log. I primarily tested with the latest versions of the Vagrant boxes, however I also tried the reported box in this case and found no difference from the other tests. My test setups

Test Setup1 (direct on hw):

system76 Gazellev2
Intel® Core™ i7-9750H CPU @ 2.60GHz × 12
32gb 3300Hz RAM
Ubuntu 18.04
Vagrant 2.2.7
Virtualbox 6.1.6

Tests was a simple Vagrantfile booting a basic box with a serial console debug printed to file. Command was

`time vagrant up`

bionic: 32s
eoan: 52s
focal: 49s

Test Setup2 virtualized:

To create a clean environment for testing, I used separate multipass VMs

1. multipass launch -m 6gb --name $SUITE-vagrant release:bionic
2. multipass mount ./ /vagrant # this was to ensure I had the Vagrantfile and could get the console log
3. multipass exec $SUITE-vagrant bash
4. sudo apt-get update && sudo apt-get dist-upgrade
5. exit and multipass restart $SUITE-vagrant
6. exec back in, sudo apt-get install virtualbox vagrant
7. time vagrant up

These times were slower due to the virtualization, but had similar deltas. Times have had the download of the boxes removed

bionic: 1:23
eoan: 1:46
focal: 1:50

Considering the double boot issue, the difference between bionic and focal makes sense. Please add more info to help identify further issues than the kernel panic and reboot