Use physical serial port on host from guest - Issues!
Posted: 25. Mar 2013, 01:56
Host Machine
Windows 7 x86 32bit (all patches up to current)
VirtualBox Version (Current as of this posting)
Guest Machine
Doesn't matter - Even tried DOS v6.22
I'll use DOS as my example here because it eliminates a bunch of farting around and probably some questions from the community as well.
I create a DOS v6.22 'guest' which has COM1 enabled and configured to use the Host Device of COM1.
On the 'host', COM1 is a virtual serial-port with a virtual modem attached - confirmed as working within the host itself.
When I try to use a terminal application from the guest configured for COM1 it reports that the that CARRIER IS HIGH (or already connected to something). Thus no communications with the virtual modem work correctly. (DTR/RTS already open?)
If I manually edit the .VBOX file and add "Enable16550A="true" then it no longer claims CARRIER IS HIGH but communications still fail with the virtual modem on the HOST.
I'm going to say this is a bug with VirtualBox as search results have returned this exact issue across MANY versions, dating back even 5 years ago.
FWIW : If I use DosBox on the host configured for 'directserial' to the virtual com which has the virtual modem attached, it works perfect without ANY issues.
Also to add, I even tried using a A REAL MODEM and REAL PHYSICAL COMPORT on the host and got the exact same problem as I do with virtuals, so this definitely eliminates any problems related to the virtual com and modem on the HOST. It seems as though when you power up the guest, it detects carrier and the lines are open right away - which is silly.
Any work-arounds for this problem ? I don't have any issues with VMware but would rather not use it either.
Windows 7 x86 32bit (all patches up to current)
VirtualBox Version (Current as of this posting)
Guest Machine
Doesn't matter - Even tried DOS v6.22
I'll use DOS as my example here because it eliminates a bunch of farting around and probably some questions from the community as well.
I create a DOS v6.22 'guest' which has COM1 enabled and configured to use the Host Device of COM1.
On the 'host', COM1 is a virtual serial-port with a virtual modem attached - confirmed as working within the host itself.
When I try to use a terminal application from the guest configured for COM1 it reports that the that CARRIER IS HIGH (or already connected to something). Thus no communications with the virtual modem work correctly. (DTR/RTS already open?)
If I manually edit the .VBOX file and add "Enable16550A="true" then it no longer claims CARRIER IS HIGH but communications still fail with the virtual modem on the HOST.
I'm going to say this is a bug with VirtualBox as search results have returned this exact issue across MANY versions, dating back even 5 years ago.
FWIW : If I use DosBox on the host configured for 'directserial' to the virtual com which has the virtual modem attached, it works perfect without ANY issues.
Also to add, I even tried using a A REAL MODEM and REAL PHYSICAL COMPORT on the host and got the exact same problem as I do with virtuals, so this definitely eliminates any problems related to the virtual com and modem on the HOST. It seems as though when you power up the guest, it detects carrier and the lines are open right away - which is silly.
Any work-arounds for this problem ? I don't have any issues with VMware but would rather not use it either.