Sun Studio 12: Debugging a Program With dbx

Debugging a Mismatched Core File

Sometimes a core file is created on one system (the core-host) and you want to load the core file on another machine (the dbx-host) to debug it. However, two problems with libraries might arise when you do so:

The user libraries and system libraries can change in patches as well as major Solaris operating environment upgrades, so this problem can even occur on the same host, if, for example, a patch was installed after the core file was collected, but before running dbx on the core file.

dbx might display one or more of the following error messages when you load a “mismatched” core file:

dbx: core file read error: address 0xff3dd1bc not available
dbx: warning: could not initialize -- trying
dbx: cannot get thread info for 1 -- generic error
dbx: attempt to fetch registers failed - stack corrupted
dbx: read of registers from (0xff363430) failed -- debugger service failed

Eliminating Shared Library Problems

ProcedureTo Eliminate the Library Problems and Debug a “mismatched” Core File

  1. Set the dbx environment variable core_lo_pathmap to on.

  2. Use the pathmap command to tell dbx where the correct libraries for the core file are located.

  3. Use the debug command to load the program and the core file.

    For example, assuming that the root partition of the core-host has been exported over NFS and can be accessed via /net/core-host/ on the dbx-host machine, you would use the following commands to load the program prog and the core file prog.core for debugging:

    (dbx) dbxenv core_lo_pathmap on
    (dbx) pathmap /usr /net/core-host/usr
    (dbx) pathmap /appstuff /net/core-host/appstuff
    (dbx) debug prog prog.core

    If you are not exporting the root partition of the core-host, you must copy the libraries by hand. You need not re-create the symbolic links. (For example, you need not make a link from to; just make sure is available.)

Things to Remember

Keep the following things in mind when debugging a mismatched core file: