Serial Port ttyS0 Not Working... Need help urgently.

[Jaun]

Serial Port /dev/ttyS0 not working.
I am trying to connect guest to host via serial port to have guest console on host.
VirtualBox setting : Port No. COM1
IRQ:4
I/O Port: ox3F8
Port Mode: Host Device
Path/Address: /dev/ttyS0

Host System: Ubuntu 16.04
Virtual Box Version: 5.1.18 r114002

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$ uname -r
4.9.4-040904-generic

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$ id
uid=1000(tauqeer) gid=1000(tauqeer) groups=1000(tauqeer),4(adm),5(tty),20(dialout),24(cdrom),27(sudo),30(dip),46(plugdev),113(lpadmin),128(sambashare),130(vboxusers)

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dmesg | grep tty
[    0.000000] console [tty0] enabled

Guest System: : Ubuntu 16.04

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$ uname -r
4.9.11

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dmesg | grep tty
[    0.000000] Command line: BOOT_IMAGE=/boot/vmlinuz-4.9.11 root=UUID=941a78ef-937f-41f9-aefd-7a6af973608b ro console=tty0 console=ttyS0,115200n8 ignore_loglevel crashkernel=384M-:128M
[    0.000000] Kernel command line: BOOT_IMAGE=/boot/vmlinuz-4.9.11 root=UUID=941a78ef-937f-41f9-aefd-7a6af973608b ro console=tty0 console=ttyS0,115200n8 ignore_loglevel crashkernel=384M-:128M
[    0.000000] console [tty0] enabled
[    0.000000] console [ttyS0] enabled
[  703.301958] 00:02: ttyS0 at I/O 0x3f8 (irq = 4, base_baud = 115200) is a 16550A
[ 1185.758922] systemd[1]: Created slice system-serial\x2dgetty.slice.

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$ id
uid=1000(kernel) gid=1000(kernel) groups=1000(kernel),4(adm),5(tty),20(dialout),24(cdrom),27(sudo),30(dip),46(plugdev),113(lpadmin),128(sambashare),999(vboxsf)

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I am getting this error-
Ioctl failed for serial host device '/dev/ttyS0' (VERR_DEV_IO_ERROR).
 The device will not work properly.

Error ID: DrvHostSerialFail
Severity: Warning

can any one help me to rectify this error.
Thanks in advance.

[Martin]

You do have a physical serial port at /dev/ttyS0 on your host hardware?

[Jaun]

Hi,
my laptop has serial port but physically i haven't connected anything to it because my motto is just to redirect guest terminal output messages to host terminal via minicom.

please do let me know if you want further information from my end.


On Host :

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sudo cat /proc/tty/driver/serial
serinfo:1.0 driver revision:
0: uart:unknown port:000003F8 irq:4
1: uart:unknown port:000002F8 irq:3
2: uart:unknown port:000003E8 irq:4
3: uart:unknown port:000002E8 irq:3
4: uart:unknown port:00000000 irq:0
5: uart:unknown port:00000000 irq:0
6: uart:unknown port:00000000 irq:0
7: uart:unknown port:00000000 irq:0
8: uart:unknown port:00000000 irq:0
9: uart:unknown port:00000000 irq:0
10: uart:unknown port:00000000 irq:0
11: uart:unknown port:00000000 irq:0
12: uart:unknown port:00000000 irq:0
13: uart:unknown port:00000000 irq:0
14: uart:unknown port:00000000 irq:0
15: uart:unknown port:00000000 irq:0
16: uart:unknown port:00000000 irq:0
17: uart:unknown port:00000000 irq:0
18: uart:unknown port:00000000 irq:0
19: uart:unknown port:00000000 irq:0
20: uart:unknown port:00000000 irq:0
21: uart:unknown port:00000000 irq:0
22: uart:unknown port:00000000 irq:0
23: uart:unknown port:00000000 irq:0
24: uart:unknown port:00000000 irq:0
25: uart:unknown port:00000000 irq:0
26: uart:unknown port:00000000 irq:0
27: uart:unknown port:00000000 irq:0
28: uart:unknown port:00000000 irq:0
29: uart:unknown port:00000000 irq:0
30: uart:unknown port:00000000 irq:0
31: uart:unknown port:00000000 irq:0

On Guest:

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$ sudo cat /proc/tty/driver/serial
[sudo] password for kernel: 
serinfo:1.0 driver revision:
0: uart:16550A port:000003F8 irq:4 tx:11746 rx:21 RTS|CTS|DTR|DSR|CD
1: uart:unknown port:000002F8 irq:3
2: uart:unknown port:000003E8 irq:4
3: uart:unknown port:000002E8 irq:3
4: uart:unknown port:00000000 irq:0
5: uart:unknown port:00000000 irq:0
6: uart:unknown port:00000000 irq:0
7: uart:unknown port:00000000 irq:0
8: uart:unknown port:00000000 irq:0
9: uart:unknown port:00000000 irq:0
10: uart:unknown port:00000000 irq:0
11: uart:unknown port:00000000 irq:0
12: uart:unknown port:00000000 irq:0
13: uart:unknown port:00000000 irq:0
14: uart:unknown port:00000000 irq:0
15: uart:unknown port:00000000 irq:0
16: uart:unknown port:00000000 irq:0
17: uart:unknown port:00000000 irq:0
18: uart:unknown port:00000000 irq:0
19: uart:unknown port:00000000 irq:0
20: uart:unknown port:00000000 irq:0
21: uart:unknown port:00000000 irq:0
22: uart:unknown port:00000000 irq:0
23: uart:unknown port:00000000 irq:0
24: uart:unknown port:00000000 irq:0
25: uart:unknown port:00000000 irq:0
26: uart:unknown port:00000000 irq:0
27: uart:unknown port:00000000 irq:0
28: uart:unknown port:00000000 irq:0
29: uart:unknown port:00000000 irq:0
30: uart:unknown port:00000000 irq:0
31: uart:unknown port:00000000 irq:0

Thanks a lot.

[Martin]

Selecting the "host device" /dev/ttyS0 would allow you to connect something at the physical port to the guest serial port (if it worked without an error message).
Redirecting the physical port doesn't work because it cannot be shared.
To connect from a terminal application on your host to the guest you probably need to use a named pipe instead.
http://www.virtualbox.org/manual/ch03.html#serialports

[Jaun]

Thanks a lot.