<p>As before, after finding these separate occasions of contribution, I then extracted the source code lines that Hellwig added or changed in each contribution in this repository. I did so by carefully cross-referencing the commits that Hellwig performed with the output of <code>git blame</code>. I specifically <a href="https://github.com/conservancy/gpl-compliance-tools/blob/master/extract-code-added-in-commits.plx">used the same script as before</a> to carefully extracted only lines that Hellwig changed or added in that repository, and placed only those contributions identifiable as Hellwig's into new files whose named matched the original filenames. This created a corpus of code that can be verifiable as added or changed by Hellwig and no one else.</p>

<h2 id="comparing-hellwigs-contributions-from-modern-linux-repository-to-vmware-sources">Comparing Hellwig's Contributions From Modern Linux Repository to VMware Sources</h2>

<p>I then used this corpus as input to CCFinderX again. Specifically, this CCFinderX comparison compared all known Hellwig-contributed material from the modern Linux repository to the partial VMware source release. CCFinderX found a ratio of similarity of 0.1615% between Hellwig's code and the source code in VMware's (partial) source release was contributed by Hellwig. CCFinderX specifically identified 23 distinct locations where substantial sections of code contributed by Hellwig appeared. These 23 locations are found in the following 19 functions: <code>mptsas_init</code>, <code>mptsas_get_linkerrors</code>, <code>megasas_build_and_issue_cmd</code>, <code>cciss_getgeo</code>, <code>mptsas_get_bay_identifier</code>, <code>phy_to_ioc</code>, <code>mptsas_sas_enclosure_pg0</code>, <code>SendIocInit</code>, <code>mptsas_parse_device_info</code>, <code>csmisas_sas_device_pg0</code>, <code>mptsas_sas_io_unit_pg0</code>, <code>mptsas_sas_io_unit_pg1</code>, <code>mptsas_sas_expander_pg1</code>, <code>mptsas_sas_enclosure_pg0</code>, <code>aac_handle_aif</code>, <code>mptsas_get_bay_identifier</code>, <code>mpt_host_page_alloc</code>, <code>mptsas_probe_one_phy</code>.</p>

<p>In <a href="https://www.linuxfoundation.org/sites/main/files/publications/estimatinglinux.html"><em>Estimating the Total Cost of a Linux Distribution</em></a>, McPherson, Proffitt, and Hale-Evans write:</p>

<blockquote>

<p>Anyone who is familiar with kernel development, for instance, realizes that the highest man-power cost in its development is when code is deleted and modified. The amount of effort that goes into deleting and changing code, not just adding to it, is not reflected in the values associated with this estimate. Because in a collaborative development model, code is developed and then changed and deleted, the true value is far greater than the existing code base. Just think about the process: when a few lines of code are added to the kernel, for instance, many more have to be modified to be compatible with that change. The work that goes into understanding the dependencies and outcomes and then changing that code is not well represented in this study.</p>