serial ports are not working

[xmrkite]

I have a serial port connected device that only works in windows xp and i just can't get it going in my windows vm with ubuntu 9.04 host. The windows program gives the error: Error Opening Port

I have serial port settings as such in virtualbox:

enable serial port checked
port number com 1, irq 4, i/o port 0x3f8
port mode: host device
port/file path: /dev/ttyS0


Here's what i get from dmesg:

dmesg | grep tty
[ 0.004000] console [tty0] enabled
[ 2.004401] serial8250: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A
[ 2.004825] 00:07: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A


Could some process be blocking the serial port's access?
What am i doing wrong? Any help is greatly appreciated.

[Perryg]

Have you tried to add the port in Win XP?
Look under control panel and ports. See if it has been installed. If not you will need to either do it from device manager or manually.

[xmrkite]

Yes, it does show up. I've tried adding a second port, removing all com ports and re-adding com1. It just won't work. Hyperterminal also says it can't open the port, so it's not just my program. Also, i even created a second vm and did a fresh install of winxp pro and it also has the exact same issues. So i don't think it's a windows issue, but a virtualbox or ubuntu issue.

Any way to check that out?

[xmrkite]

A little note: when i run aida32 enterprise system information (freebie download), it reports that irq 4 which is used for com1 is shared, whereas some irq ports it reports as exclusive. Does that mean the ubuntu and my guest os (xp pro) are both able to access the com port? Should the port be exclusive to the vm?

Just thought i'd mention that in case it helps.

-Thanks

[Perryg]

I don't know. It must be something to do with the host being Linux. I do not have a windows guest on my Linux host so I can't tell you for sure. I do know that it works works with Win Host and XP guest. I just tried it again and Hyperterm is very happy.