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Debugging the FreeBSD Kernel Transparently

Posted by kdawson on from the deep-juju dept.

An anonymous reader writes "To debug the FreeBSD kernel core dump efficiently, it is best to set up a remote debugging session between a development machine and the target machine, and remotely debug the kernel using serial communication. This article shows you how you can debug as many kernel images as you want; it becomes transparent to users once debugging starts, and your system's performance is not affected at all."

3 of 55 comments (clear)

  1. I was just about to post this story.... by concernedadmin · · Score: 3, Informative

    Hehe, good to see others saw this as an influential story of the day.
    However, I have a question that perhaps others can answer.
    What does the diagram actually work out?
    Listing 1. 25-Pin NULL modem cabling

    2 3 Transmit Data
    3 2 Receive Data
    4 5 Request to Send
    5 4 Clear to Send
    6 20 Data Set Ready and Carrier Detect
    7 7 Signal Ground
    20 6 Data Terminal Ready

    What does that mean? I thought serial -> serial is merely a connection. Do I have to solder something?

    Regards

    1. Re:I was just about to post this story.... by ampmouse · · Score: 4, Informative

      What does the diagram actually work out?
      This is a Null modem adapter. It allows you to connect to terminals, such as computers, together without a modem. It is the serial equivalent of a ethernet crossover cable.
    2. Re:I was just about to post this story.... by Spaceball_3000 · · Score: 2, Informative

      Normally from PC to modem the modem doesn't have wires crossed just a straight through cable, as the device automatically will swap certain pins like pins 2 and 3 in the device itself. But if your connecting from one computer to another using an straight through cable, the same pin like receive will connect to the same pin on the other PC (which is the receive), thus this will not work; as for normal operation you need to connect the Transmit to Receive from each PCs. Hope this helps.