diff --git a/src/gallium/drivers/swr/rasterizer/codegen/templates/gen_knobs.cpp b/src/gallium/drivers/swr/rasterizer/codegen/templates/gen_knobs.cpp
index 2f4c47a..9726cae 100644
--- a/src/gallium/drivers/swr/rasterizer/codegen/templates/gen_knobs.cpp
+++ b/src/gallium/drivers/swr/rasterizer/codegen/templates/gen_knobs.cpp
@@ -36,12 +36,14 @@
 % endfor
 #include <regex>
 #include <core/utils.h>
+#include <iostream>
 
 //========================================================
 // Implementation
 //========================================================
 void KnobBase::autoExpandEnvironmentVariables(std::string &text)
 {
+    std::cerr << "SWR_DEBUG env " << text << std::endl;
 #if (__GNUC__) && (GCC_VERSION < 409000)
     // <regex> isn't implemented prior to gcc-4.9.0
     // unix style variable replacement
@@ -51,6 +53,8 @@ void KnobBase::autoExpandEnvironmentVariables(std::string &text)
         if (end == std::string::npos)
             break;
         const std::string var = GetEnv(text.substr(start + 2, end - start - 2));
+        std::cerr << "SWR_DEBUG1 var " << text.substr(start + 2, end - start - 2) << std::endl;
+        std::cerr << "SWR_DEBUG1 val " << var << std::endl;
         text.replace(start, end - start + 1, var);
     }
     // win32 style variable replacement
@@ -71,6 +75,8 @@ void KnobBase::autoExpandEnvironmentVariables(std::string &text)
             const std::string var = GetEnv(match[1].str());
             // certain combinations of gcc/libstd++ have problems with this
             // text.replace(match[0].first, match[0].second, var);
+            std::cerr << "SWR_DEBUG2 var " << match[1].str() << std::endl;
+            std::cerr << "SWR_DEBUG2 val " << var << std::endl;
             text.replace(match.prefix().length(), match[0].length(), var);
         }
     }