Ticket #4358 (new defect)

Opened 9 years ago

Last modified 7 years ago

Break signal on serial port is not delivered to the port in vm

Reported by: vadimrapp Owned by:
Priority: major Component: uart
Version: VirtualBox 2.2.4 Keywords:
Cc: Guest type: Windows
Host type: Windows


On the host machine, I run an application that listens to COM port and reacts when the port sends Break signal. To the port I connect a device capable of sending Break signal, and the application reacts as programmed.

In Windows v.m. I specify COM port mapped to the real port on the host machine. Then I run the same application in the virtual machine and have the device send break signal. But the application in v.m. does not see it.

Break signal is described at

its implementation in Visual Basic at

I can provide the sample program demonstrating this, if needed.

Change History

comment:1 Changed 9 years ago by frank

Well, your application on the host is listening to the physical COM port? That will not work. Either your host application has to listen on the pipe or you have to use another computer which is connected to your host and which can talk with your VM over the serial line.

Or did I understood something wrong?

comment:2 Changed 9 years ago by denial

What vadimrapp wanted to say is:
When VirtualBox is configured to map the serial port to the host port and there is a device connected to the computer that pulls the rx line low to signal a break condition (that is: no stop bit after 9 zero bits in a row), then this is not reflected in bit 4 of the uart status register or no irq is generated.

comment:3 Changed 9 years ago by frank

  • Component changed from other to uart

comment:4 Changed 7 years ago by vadimrapp

is this going to be fixed?

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