I am making a driver for windows kernel and I am using COM1 for getting log of kernel, the host machine is Ubuntu and guest is qemu. Windows 10 is installed inside it. The problem is there is a bulk of data to be write on COM1. So if it has to write a line ABCDEFGHI and in the next line, it has to write JKLMNOPQ… it is doing something like ABCDEF in one line and GHIJKLMNOPQ in the second line, means one line data is incomplete and 2nd line data is also corrupting due to this… is there any lock we can apply? that if one connection is using COM1 then no any other should write on COM1?