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WinDbg kernel debugging using serial connection problem

RonyRony Member Posts: 18

I have used WinDbg for kernel debugging with serial connection with no issues in the past. However, we have a system with an Adlink controller running Win10. For some reason I am not able to do kernel debugging using the serial port, nothing is coming out of the port when Windows boots up. Once Windows is up I am able to use the port (for our application) with no problems. Any ideas?

Comments

  • Tim_RobertsTim_Roberts Member - All Emails Posts: 13,485
    via Email
    Rony wrote:
    > I have used WinDbg for kernel debugging with serial connection with no issues in the past. However, we have a system with an Adlink controller running Win10. For some reason I am not able to do kernel debugging using the serial port, nothing is coming out of the port when Windows boots up. Once Windows is up I am able to use the port (for our application) with no problems. Any ideas?

    Do you have a product number on the Adlink controller?  The kernel
    debugger doesn't use any drivers.  It pounds the serial port registers
    directly.  That means the serial port must exactly support the I/O port
    ranges and interrupt vectors that the 8250 UART uses. For COM1, it must
    respond to I/O ports 3F8-3FF and IRQ 4.  COM2 must respond to I/O ports
    2F8-2FF and IRQ 3.  If the Adlink is a PCI device with programmable port
    ranges, it cannot be used for kernel debugging.

    Tim Roberts, [email protected]
    Providenza & Boekelheide, Inc.

  • RonyRony Member Posts: 18

    Thanks Tim. The Adlink controller is an Express-HLE.

  • Tim_RobertsTim_Roberts Member - All Emails Posts: 13,485
    edited September 2018 via Email
    Rony wrote:
    > Thanks Tim. The Adlink controller is an Express-HLE.

    That board uses an Intel QM87 chipset, and it apparently has an LPC that exposes the standard COM1 and COM2 port numbers. Have you triple checked the serial port setting in "bcdedit" to make sure the baud rate matches? And you're using a regular null modem cable?

    But since you're running Win 10, you'll probably be happier with Ethernet debugging. It's a much better experience.

    Tim Roberts, [email protected]
    Providenza & Boekelheide, Inc.

  • RonyRony Member Posts: 18

    Yes I did the basic checks to make sure everything is OK but with no luck. FYI, during development we used the controller on top of a development baseboard we purchased from Adlink which provided easy to use serial connectors. The baseboard includes a super IO chip (Winbond W83627DHG) connected to the LPC bus. With that setup the serial debugging worked.

    Thanks Tim. I'll switch to Ethernet but was curious about this issue.

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