Microsoft KB Archive/872961

= FIX: Interix processes do not detect a modem's Carrier Detect signal in Windows Services for UNIX 3.5 =

Article ID: 872961

Article Last Modified on 11/15/2007

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APPLIES TO


 * Microsoft Windows Services for UNIX 3.5

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SYMPTOMS
Interix processes do not detect a modem's Carrier Detect (CD) signal in Microsoft Windows Services for UNIX 3.5.



CAUSE
The COM port is not released after an Interix process that uses the port exits. This problem prevents other processes from using the COM port. Processes that are prevented from using the port include non-Interix processes.



RESOLUTION
A supported hotfix is now available from Microsoft. However, this hotfix is intended to correct only the problem that this article describes. Apply this hotfix only to systems that are experiencing this specific problem.

To resolve this problem, submit a request to Microsoft Online Customer Services to obtain the hotfix. To submit an online request to obtain the hotfix, visit the following Microsoft Web site:

http://go.microsoft.com/?linkid=6294451

Note If additional issues occur or any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. To create a separate service request, visit the following Microsoft Web site:

http://support.microsoft.com/contactus/?ws=support

Prerequisites
No prerequisites are required.

Restart Requirement
You must restart the computer because the POSIX subsystem is replaced when you install the hotfix.

Hotfix Replacement Information
This hotfix does not replace any other hotfixes.

File Information
The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in coordinated universal time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel.   Date         Time   Version            Size    File name --  14-Jul-2004  01:59  8.0.1969.12       131,072  Posix.exe 14-Jul-2004 01:59  8.0.1969.12       104,448  Psxrun.exe 14-Jul-2004 01:59  8.0.1969.12       763,904  Psxss.exe



WORKAROUND
To work around this problem, configure the modem to make sure that the CD signal is always transmitted.

Note This workaround may have unexpected results in some applications because the CD signal is sent before the remote terminal is actually connected.



STATUS
Microsoft has confirmed that this is a bug in the Microsoft products that are listed in the &quot;Applies to&quot; section.



MORE INFORMATION
Interix does not start receiving data from a modem until the CD pin is signaled. The CD pin is also known as the Receive Line Signal Detect (RLSD). Generally, modems set this pin after they negotiate a connection with the remote modem. However, direct computer-to-computer connections are ordinarily configured so that the CD is always signaled.

The modem's settings may affect whether this problem occurs. Also, the problem appears to be more likely to occur with some serial drivers. For example, the problem is more likely to occur on Microsoft Windows Server 2003 than on Windows 2000 Server.

This issue does not apply to direct computer-to-computer connections.

For more information about Windows Services for UNIX, visit the following Microsoft Web site:

http://technet.microsoft.com/en-us/interopmigration/bb380242.aspx

Keywords: kbbug kbfix kbqfe kbhotfixserver KB872961

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