Technical Q&A QA1019

Can't attach during two-machine debugging with GDB

Q: I have a simple two machine network for doing two-machine debugging with GDB on Mac OS X. I try to attach to the target machine using its IP address such as:

    attach 111.22.33.44

But I always get these errors back:

    kdp_bind_remote: unable to resolve host "111.22.33.44"
    unable to create connection for host "111.22.33.44":RR_LOOKUP

Why can't I attach to the target machine?

A: You are probably running a version of Mac OS X older than 10.1. Prior to 10.1, GDB's attach command expects a hostname; an IP address won't work (r. 2499453). The remainder of this Q&A assumes you can't upgrade your system to Mac OS X 10.1 or later.

If your network has a domain name server, make sure that the target machine's hostname and IP address are defined in the DNS.

If you don't have a DNS on the network, such as the case where you've just hooked two machines together with a crossover cable or a standalone hub, you'll need to define hostnames on both systems in their local NetInfo databases. (This is equivalent to setting up a hosts file on Mac OS 9 or UNIX.)

Here are the steps to do this:

1. Launch /Applications/Utilities/NetInfo Manager.
2. To allow editing the NetInfo database, click the lock button in the lower left corner of the window.
3. Enter your admin password and click OK.
4. In the second column of the browser view, select the node named "machines". You'll see entries for -DHCP-, broadcasthost, and localhost in the third column.
5. The quickest way to create a new entry is to duplicate an existing one. So select the "localhost" item in the third column.
6. Select Duplicate from the Edit menu.
7. A confirmation alert will appear. Click "Duplicate".
8. A new entry called "localhost copy" will appear, and its properties will be shown below the browser view. Double click the value of the "ip_address" property and enter the IP address of the other machine.
9. Double click the value of the "name" property and enter the hostname you want for the other machine. (This is the name you'll use in the GDB attach command.)
10. Single click the "serves" property and select Delete from the Edit menu.
11. Choose Save from the File menu.
12. A confirmation alert will appear. Click "Update this copy".
13. Repeat steps 6-12 for each additional host entry you wish to add, otherwise choose Quit from the NetInfo Manager menu. You do not need to reboot.

[Jun 02, 2003]