xtensa-lx106-elf-gcc -L/home/ubuntu/ESP8266_RTOS_SDK/lib -Wl,--gc-sections -nostdlib -T/home/ubuntu/ESP8266_RTOS_SDK/ld/eagle.app.v6.ld -Wl,--no-check-sections -u call_user_start -Wl,-static -Wl,--start-group -lcirom -lcrypto -lespconn -lespnow -lfreertos -lgcc -lhal -ljson -llwip -lmain -lmesh -lmirom -lnet80211 -lnopoll -lphy -lpp -lpwm -lsmartconfig -lspiffs -lssl -lwpa -lwps user/.output/eagle/debug/lib/libuser.a sample_lib/.output/eagle/debug/lib/libsample.a -Wl,--end-group -o .output/eagle/debug/image/eagle.app.v6.out
/home/ubuntu/ESP8266_RTOS_SDK/lib/libcirom.a(lib_a-time.o):(.irom0.literal+0x0): undefined reference to `_gettimeofday_r'
/home/ubuntu/ESP8266_RTOS_SDK/lib/libcirom.a(lib_a-time.o): In function `time':
/home/wjg/Repo/esp-open-sdk/crosstool-NG/.build/src/newlib-2.0.0/newlib/libc/time/time.c:46: undefined reference to `_gettimeofday_r'
collect2: error: ld returned 1 exit status
使用 RTOS_SDK 编译过程中出现lib中变量未定义，导致编译出错，急求如何解决？？
