"-serial telnet::xxxx,server" causes "Device 'serial0' is in use"

[Thierry Briot]

I start qemu version 4.2.50 in a first terminal :

$ sudo ./qemu-system-hppa -boot d -serial telnet::4441,server -drive if=scsi,bus=0,index=6,file=./hpux.img,format=raw -serial mon:stdio -D /tmp/foo -nographic -m 512 -d nochain -cdrom ./HPUX_9.05_Installation_Disc_S700.iso -D /tmp/foo -net nic,model=tulip -net tap

qemu-system-hppa: -serial telnet::4441,server: info: QEMU waiting for connection on: disconnected:telnet:0.0.0.0:4441,server

In another terminal, I launch "telnet localhost 4441"

And in the qemu window I have the following error:

Unexpected error in qemu_chr_fe_init() at chardev/char-fe.c:220:
qemu-system-hppa: Device 'serial0' is in use

[Laurent Vivier (laurent-vivier)]

Try top put "-serial mon:stdio" before "-serial telnet::4441,server"

[Thierry Briot (tebounet)]

Effectively, no more error !
Now, my hppa machine is booted on its installation support for HP-UX 10.20, et I am connected with telnet in an other terminal. I don't know what I must enter now (on a real machine, the installation starts automatically, if I remember well what I did in 1990 !)

[Thierry Briot (tebounet)]

If I use an installation support HP-UX 11.00, the installation starts automatically. Then, it finds no disk for installation, but I will work on the drive option of qemu to resolve this trouble.
Thanks a lot for your help !

[bpotato (imapotato2)]

I would observe that it would be much better if the order of the -serial arguments did not matter so much. I know gcc has the same sort of madness (for instance), but it sure isn't intuitive.

But in my case, when you do the -serial things out of order, you end up with a segfault.
That can't be the intended behavior.

[Peter Maydell (pmaydell)]

Yes, a segfault is definitely a bug. Can you give instructions to reproduce that (full command line, any necessary images) ? The example originally reported in this bug doesn't seem to be a segfault.

[Thierry Briot (tebounet)]

I'm now using qemu-system-hppa version 5.2.50, and I can put "-serial mon: stdio" before or after "-serial telnet :: 4441, server" without a problem.

#qemu-system-hppa --version
QEMU emulator version 5.2.50 (v5.2.0-1300-g0e32462630)
Copyright (c) 2003-2020 Fabrice Bellard and the QEMU Project developers

For me, no more bug.

[Thomas Huth (th-huth)]

Ok, since you said that there is no more bug, I'm closing this issue now.

[Andrew Scott (ascott1)]

Reporting again. Compiled QEMU from the latest stable Git:

QEMU emulator version 6.2.50 (v6.2.0-529-gfb084237a3)
Copyright (c) 2003-2021 Fabrice Bellard and the QEMU Project developers

Exactly as original post, if I place -serial telnet::4441,server ahead of -serial mon,stdio on the command line, it dumps core and aborts.

if I flip them, it runs... BUT! The vm console output appears in the terminal where I launched qemu, I get no output in the telnet session. That's backwards. I have no access to the qemu console and can't issue commands to do things like change the CDROM.

full command startup script (this one works but output doesn't happen where I expect)

#!/bin/sh
CDROM="-cdrom HP-UX-OE-1.iso"
QEMU=/home/ascott/Documents/hpux/qemu/qemu/build/qemu-system-hppa
IMAGE=/home/ascott/Documents/hpux/hpux.img
$QEMU -boot d -serial mon:stdio -serial telnet::4441,server -drive if=scsi,bus=0,index=6,file=$IMAGE,format=raw -nographic -m 512 -d nochain $CDROM -net nic,model=tulip -net user

This one dumps core with the serial0 error from the originla post:

#!/bin/sh
CDROM="-cdrom HP-UX-OE-1.iso"
QEMU=/home/ascott/Documents/hpux/qemu/qemu/build/qemu-system-hppa
IMAGE=/home/ascott/Documents/hpux/hpux.img
$QEMU -boot d -serial telnet::4441,server -serial mon:stdio -drive if=scsi,bus=0,index=6,file=$IMAGE,format=raw -nographic -m 512 -d nochain $CDROM -net nic,model=tulip -net user

ascott@vmhost01:~/Documents/hpux$ sh ./install-hpux.sh
qemu-system-hppa: -serial telnet::4441,server: info: QEMU waiting for connection on: disconnected:telnet:0.0.0.0:4441,server=on
Unexpected error in qemu_chr_fe_init() at ../chardev/char-fe.c:220:
qemu-system-hppa: Device 'serial0' is in use
Aborted (core dumped)

[Thomas Huth (th-huth)]

Hi Andrew! The QEMU project does not use this bug tracker anymore - could you please open a new issue here: https://gitlab.com/qemu-project/qemu/-/issues - Thanks!