Host: Windows 7.
Guest: Customized Linux 2.6, with all output redirected to serial port.
I am going to debug the guest OS with a serial communication program under the host Windows 7.
com0com project does a great job to emulate serial port. But "The com0com.sys is a test-signed kernel-mode driver that will not load by default". I have to press F8 during Windows 7 boot or use "Test Mode" with a watermark in the corner. —- So ugly.
Using pipe is a good idea.
In VirtualBox, set the "Serial Ports" with "Host Pipe" Port Mode, enable "Create Pipe" with Port/File Path "\.pipemy_com". Start the virtual machine.
Open PuTTY, select to use "Serial" as connection type, and "\.pipemy_com" as Serial Line, with 115200 Speed. Configure the serial line as 8N1 (Data bits: 8, Stop bits: 1, Parity: None, Flow control: None). Configuration has been done, Open it!
Remember to start virtual machine before you open PuTTY pipe.