﻿id	summary	reporter	owner	description	type	status	component	version	resolution	keywords	cc	guest	host
18671	Cannot get real data from serial interface	hykwok		"I encounter serial port problem in VirtualBox 6.0.8.[[BR]]
It is my testing procedure:

Setup Host environment:

1. The host system is Windows 7 64 bits.

1.1 Download Virtual COM Port Driver (Standard Demo version) from here:  https://www.eltima.com/products/vspdxp/ [[BR]]
1.2 Install Virtual COM Port Driver and create a pair of Virtual COM Port (In my case, they are COM2 and COM4)[[BR]]
1.3 Downlaod Putty (Windows version) from here:  https://putty.org/ [[BR]]

2. Create Ubuntu 18.04 with Virtual Box 6.0.8[[BR]]

2.1 Create a virtual machine that uses Ubuntu 18.04.[[BR]]
2.2 Enable serial port 1 for this virtual machine and set the ""port mode"" to ""Host Device"" and the ""path/Address"" to one of the above virtual COM port (in my case it is COM2)[[BR]]
2.3 Install putty package:[[BR]]

sudo aptitude install putty[[BR]]
sudo aptitude install putty-tools[[BR]]

3. Start putty (windows side)and connect to COM4[[BR]]

4. Start Ubuntu 18.04 and then start putty (Linux side):
sudo putty

5. Sends 256 bytes data from Windows host to Linux guest by putty application
Now, you should get the data what you have inputted instantly

6. Close the Linux side's putty but DO NOT close the windows side's putty.

7. Sends another 256 bytes from Windows host to Linux guest.

8. Start the Linux side's putty again (sudo putty)

9. Sends data from Windows host to Linux guest.
Now, you CANNOT get the data what you have inputted instantly.

I find that virtualBox stores 221 bytes old data in the cache.
Thus, I have to shutdown the Linux guest (not reboot) to fix the problem.

P.S. This bugs may be realted to #18539
"	defect	closed	uart	VirtualBox 6.0.8	fixed	serial		Linux	Windows
