QNX Neutrino Programmer's Guide [6.5.0 SP1] - QNX Software ...

© 2012, QNX Software Systems Limited Optimizing the runtime linker
Diagnostics and debugging
dependency. As a consequence, lazy loading can’t be transparent as, for example, lazy
binding is (lazy binding doesn’t change the lookup scope, only the time of the symbol
lookup).
When you’re developing a complex application, it may become difficult to understand
how the dynamic linker lays out the internal link maps and scopes of resolution. To
help determine what exactly the dynamic linker is doing, you can use the
DL_DEBUG environment variable to make the linker display diagnostic messages.
Diagnostic messages are categorized, and the value of DL_DEBUG determines which
categories are displayed. The special category help doesn’t produce diagnostics
messages, but rather displays a help message and then terminates the application.
To redirect diagnostic messages to a file, set the LD_DEBUG_OUTPUT
environment variable to the full path of the output file.
For security reasons, the use of LD_DEBUG_OUTPUT with setuid binaries is
disabled.
Environment variables
The following environment variables affect the operation of the dynamic linker:
DL_DEBUG
Display diagnostic messages. The value can be a
comma-separated list of the following:
• all — display all debug messages.
• help — display a help message, and then exit.
• reloc — display relocation processing messages.
• libs — display information about shared objects being
opened.
• statistics — display runtime linker statistics.
• lazyload — print lazy-load debug messages.
• debug — print various runtime linker debug messages.
A value of 1 (one) is the same as all.
LD_DEBUG
A synonym for DL_DEBUG; if you set both variables,
DL_DEBUG takes precedence.
LD_DEBUG_OUTPUT
The name of a file in which the dynamic linker writes its
output. By default, output is written to stderr.
June 14, 2012 Chapter 1 • Compiling and Debugging 21