I follow the steps:
repo init -u https://android.googlesource.com/platform/manifest -b android-11.0.0_r25 repo sync -c -j8
source build/envsetup.sh lunch aosp_walleye-userdebug make
export ANDROID_PRODUCT_OUT=/Users/zgxgoo/android/mnt/out/target/product/walleye fastboot flashall -w fastboot reboot Then the bootloader show: ERROR:Slot Unbootable: Load Error