Add new fuzz_*features.conf files to add more CONFIG_ when fuzzing

The goal of these new files is to:
1. Fuzz more code
2. Reduce the configuration gap between fuzzed SOF and the real thing.

See the fuzz_features.conf header for more details.

Signed-off-by: Marc Herbert <marc.herbert@intel.com>

app/configs/fuzz_IPC3_features.conf

@@ -0,0 +1 @@
+# See main file fuzz_features.conf

app/configs/fuzz_IPC4_features.conf

@@ -0,0 +1,4 @@
+# See main file fuzz_features.conf
+
+CONFIG_COMP_UP_DOWN_MIXER=y
+CONFIG_COMP_ARIA=y

app/configs/fuzz_features.conf

@@ -0,0 +1,48 @@
+# The goal of this file is to:
+# 1. Fuzz more code
+# 2. Reduce the gap between fuzzed SOF and the real thing.
+
+# KConfig warnings are NOT fatal so you must always INSPECT build logs when changing
+# .conf files. See https://github.com/thesofproject/sof/issues/9386
+
+# Note 1. is not as simple as enabling as many CONFIG_ as possible. Enabling some CONFIG_
+# can technically _disable_ some code paths. But the opposite is more common so let's add
+# more.
+
+# In the longer term we should have some more elaborate configuration framework to reduce
+# duplicate/diverge between fuzzing and production but also across product
+# generations. Something like config fragments including each other? Not something as
+# complicated as Yocto fragments but something more flexible than
+# https://docs.zephyrproject.org/latest/build/kconfig/setting.html#initial-conf
+#
+# Discuss in https://github.com/thesofproject/sof/issues/9386
+
+# Many of these features are too far from IPC to make any fuzzing difference. But as long
+# as they reduce the size of the textual difference between build-fuzz/zephyr/.config and
+# build-xxx/zephyr/.config, they make that manual comparison easier which is still a win.
+
+
+CONFIG_COUNTER=y
+
+CONFIG_PROBE=y
+
+CONFIG_CRYPTO=y
+
+CONFIG_LOG_TIMESTAMP_64BIT=y
+CONFIG_MM_DRV=y
+
+CONFIG_DMA=y
+
+CONFIG_DAI=y
+
+CONFIG_PM_DEVICE=y
+CONFIG_POWER_DOMAIN=y
+
+CONFIG_COMP_SRC_IPC4_FULL_MATRIX=y
+CONFIG_COMP_CROSSOVER=y
+CONFIG_COMP_DRC=y
+CONFIG_COMP_KPB=y
+
+CONFIG_MATH_LUT_SINE_FIXED=y
+CONFIG_MATH_EXP=y
+CONFIG_MATH_IIR_DF2T=y

scripts/fuzz.sh

@@ -111,6 +111,9 @@ main()
   # https://docs.zephyrproject.org/latest/build/kconfig/setting.html#initial-conf
   local conf_files_list='prj.conf;boards/native_sim_libfuzzer.conf'
 
+  conf_files_list+=';configs/fuzz_features.conf'
+  conf_files_list+=";configs/fuzz_IPC${IPC}_features.conf"
+
   # Note there's never any reason to delete fuzz_corpus/.
   # Don't trust `west build -p` because it is not 100% unreliable,
   # especially not when doing unusual toolchain things.