fuzz: doc: add info about afl-system-config for macOS #32175

1. 
   brunoerg commented at 4:17 pm on March 31, 2025: contributor

   afl-system-config adjusts the shared memory segment size limits and configures kernel parameters for better fuzzing performance. Since macOS has more conservative values on shared memory, it’s necessary to run afl-system-config, or manually adjust the values to fuzz with AFL++.

   e.g.:

   0kern.sysv.shmmax: 524288000
   1kern.sysv.shmmin: 1
   2kern.sysv.shmseg: 48
   3kern.sysv.shmall: 131072000
   

2. fuzz: doc: add info about `afl-system-config` for macOS 66572c2745
3. 
   DrahtBot commented at 4:17 pm on March 31, 2025: contributor

   The following sections might be updated with supplementary metadata relevant to reviewers and maintainers.

   Code Coverage & Benchmarks

   For details see: https://corecheck.dev/bitcoin/bitcoin/pulls/32175.

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   Concept ACK	janb84

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4. DrahtBot added the label Tests on Mar 31, 2025
5. in doc/fuzzing.md:190 in 66572c2745

   186@@ -187,6 +187,8 @@ $ cmake -B build_fuzz \
   187 $ cmake --build build_fuzz
   188 # For macOS you may need to ignore x86 compilation checks when running "cmake --build". If so,
   189 # try compiling using: AFL_NO_X86=1 cmake --build build_fuzz
   190+# Also, it might be required to run afl-system-config to adjust the shared
   

   ---

   ---

   

   janb84 commented at 5:59 pm on April 14, 2025:

   0# Also, it might be required to run "afl-system-config" to adjust the shared
   

   Small nit, to keep it in the same style as line 188

6. 
   janb84 commented at 6:02 pm on April 14, 2025: contributor

   Concept ACK 66572c2

   Small style NIT, to keep the comment in the same style as 2 lines before. Not blocking.

   Overall small addition to the documentation, provides extra valuable information, looks good to me.

Contributors
brunoerg DrahtBot janb84

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Tests