Re: Guest Ubuntu 18.04 fails to boot with -serial mon:stdio, cannot find ttyS0.

[Peter Maydell]

On Wed, 10 Nov 2021 at 18:56, David Fernandez <david.fernandez@sen.com> wrote:
>
> As I have not hear anything yet, I thought I would summarize the current
> status
> for this problem. Please, let me know if any other tests or information are
> needed.
>
> I am running qemu-system-x86_64 v5.2.0 (also tried v6.1.0 and top of
> master) on:
>     - aarch64 (Jetson AGX Xavier) with Ubuntu 18.04.5 as a host
> (compiled from
>       git sources as distro version for it was 2.11, which is too old),
> and on
>     - x86_64 (my laptop) with Fedora 34 as a host (here the
> qemu-system-x86_64
>       distro version is 5.2.0).
>
> Running Ubuntu 18.04.6 server install cdrom (also tried Ubuntu 20.04.3)
> as the
> guest.
>
> The following services fail on the Jetson, but not on the laptop. The
> first one
> is the ttyS0 console, which seems the most important thing as it is provided
> directly by the virtual emulation (-serial mon:stdio):
>
> [ TIME ] Timed out waiting for device dev-ttyS0.device.

I'm pretty sure this isn't actually a problem with the emulation
of the serial device (after all you are seeing all these messages
so far on the serial console, right?). The problem is that the
udev machinery that creates nodes in /dev is being too slow
(or possibly is failing for some other reason, but given all the
other timeouts I'm guessing "everything is too slow") and so
the systemd unit that is waiting for /dev/ttyS0 to be created
times out.

-- PMM