DPCL Linux Port:

Project Lead: Dave Wootton

Project Goals:

The purpose of this project is to port DPCL to Linux running on Intel Pentium-class hardware.

How To Get Started:

You can begin by obtaining the DPCL source code and experimenting with that code.

The simplest way to obtain the source code is to download the latest version of the gzipped tar file from the DPCL project's download page, and unpack that tar file. This tar file will unpack into a complete DPCL source directory structure, but will not contain the CVS control files and directories.

You can also check out the source code from CVS. To do this, set the CVSROOT to :pserver:anoncvs@oss.software.ibm.com:/usr/cvs/dpcl then use the cvs checkout command to get the source code.

If you have changes you would like us to consider including in DPCL, send them to us by email.

Any updates you send us should be created as patches that can be applied to the DPCL source, using the patch program. Ideally, the patches should be applicable to the latest level of DPCL in CVS. They should not be applicable to anything older than the latest official, tagged level in CVS..

Contact Information:

If you have comments, questions, or code patches, you can send us e-mail at dpcl-develop@www-124.ibm.com

Design Information:

There is no design documentation available at this time.

Status:

The current port is a subset of the function available in the AIX version of DPCL, with the following limitations

• Only target applications written in 'C' are supported
• Target applications to be instrumented must be single threaded.
• Parallel applications using MPI are not supported.

Phase one of probe module support is available. The code can be extracted from the development (default) code branch in cvs.

There are two differences between the Linux implementation and the AIX implementation

• The probe modules must be compiled with the -gdwarf-2 -shared and -fpic gcc compiler flags.
• All functions in the probe module are implicitly exported.

Phase one has the following restrictions:

• Unloading a probe module does not work.
• Linux BPatch loads symbol information on demand, rather than when the module is initially loaded. The logic which manages this needs to be finished. Currently, multiple requests for symbol information may result in multiple copies of the data being loaded.
• The original BPatch code had a restriction that only one instance of a source file could be loaded. If a second module was compiled from a source file with the same name, an attempt to load that probe module would trigger an assert. Currently, the reference to the second source file is discarded

These restrictions will be removed in a future update.

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