COM Ports not working in OS/2

[mipri]

Hello,

since VirtualBox 6.0.0 the emulated COM-Ports are no longer usable with OS/2. The ports are visible to the guest and can be accessed, but the applications using such a port freeze after transferring some data.

If the application is frozen, the corresponding process remains in the task list and cannot be removed, not even by using the "kill feature" (CTRL-tasklist in the launchpad). The system does not perform a shutdown any more and has to be terminated by pressing CTRL-ALT-DEL.

It does not matter if the emulated COM-port in the guest is connected to a real, physical RS232-Interface on the host or an virtual COM-Port created by an USB<->RS232 adapter. In fact, the problems even occurs if the port mode is set to "not connected" the the VM settings.

The serial ports did work fine in VirtualBox 5.x.

[socratis]

Does this happen with all 6.x.x releases, i.e. 6.0.0, 6.0.2, 6.0.4 and 6.0.6?
What if you revert to 5.2.28?

[mipri]

I did not use version 6.0.0, but 6.0.2 and 6.0.4 had the same problem.

With version 5.2.28 the COM ports are working fine.

[socratis]

Can you please try with 6.0.0? It may seem trivial, but if the developers know that this is a 6.x issue and not a 6.0.0 -> 6.0.2 issue, it helps a lot...

[andyp73]

As I recall from previous discussions with the devs there was a significant rewrite of the serial port code for 6.0.x. There are probably still a few minor regressions hiding in there for corner cases.

-Andy.

[mipri]

I've tried version 6.0.0 today and it has the same problem as versions 6.0.2 to 6.0.6.

[michaln]

Does it really happen with 6.0.6? It's not clear from the above. 6.0.6 did include additional fixes.

If it does happen with 6.0.6, please provide a specific and detailed recipe for reproducing the problem, ideally only using tools that come with the OS.

[mipri]

Does it really happen with 6.0.6? It's not clear from the above.

Yes, it definitely happens with 6.0.6.

6.0.6 did include additional fixes.

I had similar problems with the COM ports in my VM running Windows XP if VB was 6.0.2 or 6.0.4. For Windows, these problems are fixed in 6.0.6, but for OS/2 they persist.

Example: ZOC from emtec is a serial terminal emulator. The pretty old version 3.17 I am using was available for OS/2 and Windows 32 bit. I am using it with both systems, so I can compare how it worked with different versions of VB:

5.2.24: ZOC works with OS/2 and Windows XP
5.2.28: ZOC works with OS/2, did not test with Windows XP

6.0.0: ZOC not working with OS/2, did not test with Windows XP
6.0.2: ZOC not working with OS/2 and not working with Windows XP
6.0.4: same as 6.0.2
6.0.6: ZOC still not working with OS/2, but working again with WIndows XP

If it does happen with 6.0.6, please provide a specific and detailed recipe for reproducing the problem, ideally only using tools that come with the OS.

ZOC 3.17 is still available for OS/2 and Windows with free download from http://www.emtec.com/downloads/zoc/zoc3. The unlicensed version has no restrictions except a nag screen after each file download.

Set up a COM port for the guest OS. It does not matter what is connected to this port, so the port mode can be set to "not connected". Install ZOC and set it up to use this COM port. Then try to connect, type some keys on the keyboard, try to disconnect, to re-connect and play a bit around with it. Very soon ZOC will freeze. Try to close ZOC, there will a process remain in the task list that can not be killed, and it is not possible to shutdown OS/2, except with CTRL-ALT-DEL. If you do the same with Windows XP and VB 6.0.6, nothing will freeze.

As a tool that came with OS/2, you also could use Hype Access Lite. It was part of the OS/2 Bonuspak and usually is installed in C:\BonusPak\halite. It's the same as with ZOC: try to open a connection, to disconnect, to re-connect. Also Hyper Access Lite freezes on my system after just a few attempts. I've attached a log recorded while playing with HyperAccess until it freezes.

My guest is running OS/2 Warp 4.5 with FP 15 and DD FP 2. It is using the original drivers for the serial ports, no sio2k.sys or whatever.

[MathieuM]

dear all
i have same issue with virtual box V6, serial communication is not working, and it's working fine if i switch to old version 5
Context:
- Host : Win7 pro
- Guest : OS2 /warp 4.5
we use it to connect to old PLC machine with seriel port (embeded COM1)

[Felix_g]

With v6.1 it doesn't work either.

Host: Windows 10.
Guest: Ecomstation and OS/2 Warp 4.5

I have added data in ticket 18668 (https://www.virtualbox.org/ticket/18668) to try to find a solution.

[michaln]

Set up a COM port for the guest OS. It does not matter what is connected to this port, so the port mode can be set to "not connected". Install ZOC and set it up to use this COM port. Then try to connect, type some keys on the keyboard, try to disconnect, to re-connect and play a bit around with it. Very soon ZOC will freeze. Try to close ZOC, there will a process remain in the task list that can not be killed, and it is not possible to shutdown OS/2, except with CTRL-ALT-DEL. If you do the same with Windows XP and VB 6.0.6, nothing will freeze.

For the record, this problem (ZOC hanging on exit, unkillable) was reproducible with a serial port that isn't attached to anything, but it didn't happen with a serial port attached e.g. to a host pipe. The problem has now been fixed for the "Disconnected" serial port emulation; the issue was not reporting the CTS signal as active when nothing was attached.