按照官方例程跑的，为何会出错呢？
[1/6] cmd.exe /C "cd /D C:\ESP32\esp-who\esp-who\examples\human_face_recognition\build\bootloader && C:\ESP32\.espressif\tools\cmake\3.20.3\bin\cmake.exe --build ."
[1/1] cmd.exe /C "cd /D C:\ESP32\esp-who\esp-who\examples\human_face_recognition\build\bootloader\esp-idf\esptool_py && python C:/ESP32/ESP-IDF4.4/components/partition_table/check_sizes.py --offset 0x8000 bootloader 0x1000 C:/ESP32/esp-who/esp-who/examples/human_face_recognition/build/bootloader/bootloader.bin"
Bootloader binary size 0x50e0 bytes. 0x1f20 bytes (28%) free.
[2/4] cmd.exe /C "cd . && C:\ESP32\.espressif\tools\xtensa-esp32s2-elf\esp-2021r2-8.4.0\xtensa-esp32s2-elf\bin\xtensa-esp32s2-elf-g++.exe -mlongcalls @CMakeFiles\human_face_recognition_lcd.elf.rsp -o human_face_recognition_lcd.elf && cd ."
FAILED: human_face_recognition_lcd.elf
cmd.exe /C "cd . && C:\ESP32\.espressif\tools\xtensa-esp32s2-elf\esp-2021r2-8.4.0\xtensa-esp32s2-elf\bin\xtensa-esp32s2-elf-g++.exe -mlongcalls @CMakeFiles\human_face_recognition_lcd.elf.rsp -o human_face_recognition_lcd.elf && cd ."
c:/esp32/.espressif/tools/xtensa-esp32s2-elf/esp-2021r2-8.4.0/xtensa-esp32s2-elf/bin/../lib/gcc/xtensa-esp32s2-elf/8.4.0/../../../../xtensa-esp32s2-elf/bin/ld.exe: esp-idf/freertos/libfreertos.a(port_common.c.obj):(.literal.main_task+0x10): undefined reference to `app_main'
c:/esp32/.espressif/tools/xtensa-esp32s2-elf/esp-2021r2-8.4.0/xtensa-esp32s2-elf/bin/../lib/gcc/xtensa-esp32s2-elf/8.4.0/../../../../xtensa-esp32s2-elf/bin/ld.exe: esp-idf/freertos/libfreertos.a(port_common.c.obj): in function `main_task':
C:/ESP32/ESP-IDF4.4/components/freertos/port/port_common.c:118: undefined reference to `app_main'
collect2.exe: error: ld returned 1 exit status
ninja: build stopped: subcommand failed.