First, I'd like to thank Scott (for comment #43) and Alejandro (comment #45) - 
it seems
there's a bunch of LP bugs orbiting around the same issue: Ubuntu isn't bootable
if we set an invalid serial console on kernel command-line (and have no "quiet"
option there), it seems.

Specially, I'd like to thank WGH for the great debug work on comment #46, it 
me a lot of time debugging, and you're right, it's a pain to debug issues 
to console, not easy to output stuff. I used the trick to echo debug messages
to the right console, helped me to narrow down some stuff. But in the end, 
debug exposed what seems to be the major problem here: due to a return value
carriage among functions (starting with printf returning 1 due to bad console),
we end up looping in checkfs(), preventing the boot.

I respectfully disagree with Scott: although I consider there are potential 
on kernel in the console "front", we have here a userspace bug in init scripts,
due to an error in printf if console is not correctly set. I don't agree we 
let it alone and pursue a kernel-only solution, specially due to the easy nature
of reproducing the issue, and hard nature of debugging it. Also, it seems there
are long-term bugs reporting similar issues, it bothers a bunch of people.

I cannot be 100% sure we don't have more issues than the checkfs() one found by
WGH, but this one is definitely an issue and an easy one to fix; I proposed a 
simple fix in the below test-only PPA:

The more users can test that, more confidence we'll have that there are no more
initramfs bugs if console is wrongly set. I agree with the idea of showing some
output message on kmsg if serial console is broken, it's helpful. We can do that
as part of an improvement, maybe in the same "commit" as the fix.

More opinions are welcome on this matter, of course. If my solution either 
resolve the issue for users or is not the optimal one, let's discuss 
to fix this initramfs long-term flaw.



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  Cloud images fail to boot when a serial port is not available

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