Linux boot slows to a crawl when serial port is enabled for serial getty (console).

[chuckwolber]

This issue first appeared in VirtualBox 5.2.6. This issue does *NOT* exist in VirtualBox 5.1.32 or earlier.

We are using a custom 64 bit Linux OS that uses a serial getty on ttyS0. Prior to VirtualBox 5.2.6, the boot took less than ten seconds. The boot now takes about 20 minutes under VirtualBox 5.2.6.

The UART settings in question are as follows:

UART 1: I/O base: 0x03f8, IRQ: 4, attached to pipe (server) '/tmp/ttyS0'
UART 2: I/O base: 0x02f8, IRQ: 3, attached to pipe (server) '/tmp/ttyS1' 

The boot returns to normal when using VirtualBox 5.2.6 if UART 1 is turned off. Or, we can leave both UARTs on and revert back to VirtualBox 5.1.32.

I have attached log files from VirtualBox 5.2.6. One log file is with UART 1 turned on (slow boot), and the other is with UART 1 turned off (fast boot).

[chuckwolber]

Slow boot log.

[chuckwolber]

Fast boot log.

[chuckwolber]

Boot console screen shot at the moment things slow down to a crawl.

[aeichner]

To what kind of application is the named pipe connected, some standard tool available we can use for testing or something else?

[aeichner]

Seems the slowdown is caused when there is no application connected to the other end, everything is back to normal as soon as it connects.

[chuckwolber]

Replying to aeichner:

Seems the slowdown is caused when there is no application connected to the other end, everything is back to normal as soon as it connects.

To add to this - things seems to work fine when VirtualBox Additions are installed. Unfortunately that is not an option in this case, as this is a very minimal bootstrap OS.

[chuckwolber]

Testing has shown that this problem does not occur when using VirtualBox 5.2.0.

[chuckwolber]

Update: This problem still exists in VirtualBox 5.2.20 (r125813).

[danham]

Has there been any progress on this or workarounds found?

I am experiencing the same issue. As reported above, when there is no application connected the console output slows to a crawl. When connected (with socat or minicom) everything goes back to normal. However, Virtualbox Additions are installed in the guest.

Host info:

$ VBoxManage --version
6.0.6r130049

$ sw_vers
ProductName:    Mac OS X
ProductVersion: 10.14.4
BuildVersion:   18E226

Guest info:

$ cat /etc/os-release
PRETTY_NAME="Debian GNU/Linux 9 (stretch)"
NAME="Debian GNU/Linux"
VERSION_ID="9"
VERSION="9 (stretch)"
ID=debian
HOME_URL="https://www.debian.org/"
SUPPORT_URL="https://www.debian.org/support"
BUG_REPORT_URL="https://bugs.debian.org/"

$ VBoxControl version
Oracle VM VirtualBox Guest Additions Command Line Management Interface Version 6.0.6
(C) 2008-2019 Oracle Corporation
All rights reserved.

6.0.6r130049

[chuckwolber]

Update: This problem still exists on VirtualBox 6.0.12

[chuckwolber]

Update: This problem still exists on VirtualBox 6.0.18 (r136238)

[chuckwolber]

Update: This problem still exists on VirtualBox 6.1.12 (r139181)

[chuckwolber]

Update: This problem still exists on VirtualBox 6.1.28 (r147628)