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-rw-r--r--docs/env_variables.txt13
1 files changed, 8 insertions, 5 deletions
diff --git a/docs/env_variables.txt b/docs/env_variables.txt
index d854ea8d..8e2723d7 100644
--- a/docs/env_variables.txt
+++ b/docs/env_variables.txt
@@ -82,6 +82,9 @@ discussed in section #1, with the exception of:
- TMPDIR and AFL_KEEP_ASSEMBLY, since no temporary assembly files are
created.
+ - AFL_INST_RATIO, as we switched for instrim instrumentation which
+ is more effective but makes not much sense together with this option.
+
Then there are a few specific features that are only available in llvm_mode:
LAF-INTEL
@@ -108,16 +111,16 @@ Then there are a few specific features that are only available in llvm_mode:
OTHER
=====
- - Setting export AFL_LLVM_NOT_ZERO=1 during compilation will use counters
+ - Setting LOOPHEAD=1 optimized loops. afl-fuzz will only be able to
+ see the path the loop took, but not how many times it was called
+ (unless its a complex loop).
+
+ - Setting AFL_LLVM_NOT_ZERO=1 during compilation will use counters
that skip zero on overflow. This is the default for llvm >= 9,
however for llvm versions below that this will increase an unnecessary
slowdown due a performance issue that is only fixed in llvm 9+.
This feature increases path discovery by a little bit.
-Note that AFL_INST_RATIO will behave a bit differently than for afl-gcc,
-because functions are *not* instrumented unconditionally - so low values
-will have a more striking effect. For this tool, 0 is not a valid choice.
-
3) Settings for afl-fuzz
------------------------