CONFIG_NO_SCAN_PROCESSING=y is broken - causes wpa_supplicant/bss.c:1575: undefined reference to `wpa_scan_res_match'

[Ivan Ivanov]

Dear friends, I am trying to build a super minimalistic busybox image
that has Linux kernel and wpa_supplicant. So I am disabling as many
configs as possible while preserving the 802.11n / WPA2 functionality.
However, even with the latest v2.11 release of hostap/wpa_supplicant -
trying to do CONFIG_NO_SCAN_PROCESSING=y results in the following
error, while without it everything is OK :

  CC  ../src/l2_packet/l2_packet_linux.c
MYPATH/x86_64-linux-musl-cross/bin/../lib/gcc/x86_64-linux-musl/11.2.1/../../../../x86_64-linux-musl/bin/ld:
MYPATH/hostap/build/wpa_supplicant/bss.o: in function
`wpa_bss_parse_ml_rnr_ap_info':
MYPATH/hostap/wpa_supplicant/bss.c:1575: undefined reference to
`wpa_scan_res_match'
collect2: error: ld returned 1 exit status
make: *** [Makefile:2010: wpa_supplicant] Error 1

Here is my config (btw if you could suggest more options for trimming
the size I will really appreciate it) :

# Core driver
CONFIG_DRIVER_NL80211=y
CONFIG_TLS=internal
CONFIG_CRYPTO=internal
CONFIG_CRYPTO_INTERNAL=y

# Minimal crypto needed for WPA2
CONFIG_INTERNAL_LIBTOMMATH=y
CONFIG_INTERNAL_SHA1=y
CONFIG_INTERNAL_AES=y

# Control interface
CONFIG_CTRL_IFACE=y
CONFIG_CTRL_IFACE_UNIX=y

# Disabled features for size reduction
CONFIG_NO_EAP=y
CONFIG_NO_WPS=y
CONFIG_NO_HOSTAPD_LOGGER=y
CONFIG_NO_ROBUST_AV=y
CONFIG_NO_RRM=y
CONFIG_NO_WMM_AC=y
CONFIG_NO_VLAN=y
CONFIG_NO_RADIUS=y
CONFIG_NO_ACCOUNTING=y
CONFIG_NO_BROWSER=y
CONFIG_NO_PKCS11_ENGINE_PATH=y
CONFIG_NO_PKCS11_MODULE_PATH=y
CONFIG_NO_OPENSC_ENGINE_PATH=y
CONFIG_NO_LOAD_DYNAMIC_EAP=y
CONFIG_NO_STDOUT_DEBUG=y
### WARNING: comment out one next config below to build ok
CONFIG_NO_SCAN_PROCESSING=y
CONFIG_NO_ROAMING=y
CONFIG_NO_DUMP_STATE=y
CONFIG_NO_CONFIG_BLOBS=y
CONFIG_REDUCED_CODE_SIZE=y
# Debugging
### CONFIG_DEBUG_SYSLOG=y
# Configuration backend
CONFIG_BACKEND_FILE=y
# Networking
CONFIG_LIBNL_TINY=y
# WiFi features
CONFIG_IEEE80211N=y           # 802.11n (WiFi 4) - most common standard
CONFIG_HT_OVERRIDES=y         # Allow HT (High Throughput) configuration

and here is a command I am using to build:

 make clean && make CC="$CC" EXTRA_CFLAGS="-Os -ffunction-sections
-fdata-sections -fno-unwind-tables -fno-asynchronous-unwind-tables
-flto -fomit-frame-pointer -fmerge-all-constants -fno-stack-protector"
LDFLAGS="-Lmytoolchain/lib -static -Wl,--gc-sections -Wl,--strip-all"
wpa_supplicant wpa_cli &&
./../../x86_64-linux-musl-cross/bin/x86_64-linux-musl-strip
./wpa_supplicant &&
./../../x86_64-linux-musl-cross/bin/x86_64-linux-musl-strip ./wpa_cli
&& ls -al ./wpa_supplicant && ls -al ./wpa_cli

Best regards,
Ivan