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

[Peter Maydell]

On Mon, 8 Nov 2021 at 18:05, David Fernandez <david.fernandez@sen.com> wrote:
> I couldn't get the stock qemu-system-x86_04 to boot correctly, as it was
> an old version 2.11.1, I decided to recompile from sources to see if
> that would fix the problem, but the problem still persists, using both
> top of master and stable-2.12 (currently on that).[ TIME ] Timed out
> waiting for device dev-ttyS0.device.

FWIW, I tried to repro this on an aarch64 server I have access to,
and I don't see that error -- the system boots (eventually) to
the installer UI.

QEMU version built: upstream git, commit 70f872ca916ac45.

Configure options:
--target-list=x86_64-softmmu --disable-tools --disable-docs

vmlinuz and initrd extracted from the iso with
isoinfo  -i ubuntu-18.04.6-live-server-amd64.iso -x '/CASPER/INITRD.;1' > initrd
isoinfo  -i ubuntu-18.04.6-live-server-amd64.iso -x
'/CASPER/VMLINUZ.;1' > vmlinuz

QEMU command:
./build/tgt-x86/qemu-system-x86_64 -boot order=dc,menu=on -cdrom
ubuntu-18.04.6-live-server-amd64.iso -nographic -serial mon:stdio -m
16384 -kernel /tmp/vmlinuz -initrd /tmp/initrd -append 'boot=casper
console=ttyS0 ---'

(I didn't bother creating any of the devices for this test, so as
you note there's a bunch of harmless complaints from the kernel
floppy driver.)

Total time to reach first screen of the text installer: 5m26s

It's maybe also worth mentioning that "emulate x86-64" is, although
a supported use case, not one that as far as I'm aware anybody is
paid to work on, so enhancements and bugfixes to it are largely
done on a volunteer basis. (This is as distinct from, for example,
"using KVM on either x86-64 or aarch64" and "emulation of aarch64
on x86-64", which have more people working on them.)

-- PMM