I have modified extlinux.conf file and reboot.
/boot/extlinux/extlinux.conf
TIMEOUT 30
DEFAULT primary
MENU TITLE L4T boot options
LABEL primary
MENU LABEL primary kernel
LINUX /boot/Image
FDT /boot/dtb/tegra194-p3668-all-p3509-0000.dtb
INITRD /boot/initrd
APPEND ${cbootargs} quiet root=/dev/nvme0n1p1 rw rootwait rootfstype=ext4 console=ttyTCU0,115200n8 console=tty0 fbcon=map:0 net.ifnames=0
# When testing a custom kernel, it is recommended that you create a backup of
# the original kernel and add a new entry to this file so that the device can
# fallback to the original kernel. To do this:
#
# 1, Make a backup of the original kernel
# sudo cp /boot/Image /boot/Image.backup
#
# 2, Copy your custom kernel into /boot/Image
#
# 3, Uncomment below menu setting lines for the original kernel
#
# 4, Reboot
# LABEL backup
# MENU LABEL backup kernel
# LINUX /boot/Image.backup
# INITRD /boot/initrd
# APPEND ${cbootargs}
dtb file has been copy to the directory:
root@123:/# ls /boot/dtb/
kernel_tegra194-p3668-all-p3509-0000.dtb tegra194-p3668-all-p3509-0000.dtb
kernel_tegra194-p3668-all-p3509-0000.dtb.sig
Boot loader log:
[0012.529] I> Loading kernel-dtb ...
[0012.529] I> Loading kernel-dtb binary from rootfs ...
[0012.529] I> rootfs path: /sdmmc_user/boot/dtb/tegra194-p3668-all-p3509-0000.dtb
[0018.727] I> lookup_linear_dir:485: Invalid file block num
[0018.728] I> ext2_walk:142: 'tegra194-p3668-all-p3509-0000.dtb' lookup failed
[0018.728] I> ext4_open_file:704: '/boot/dtb/tegra194-p3668-all-p3509-0000.dtb' lookup failed
[0018.729] E> file /sdmmc_user/boot/dtb/tegra194-p3668-all-p3509-0000.dtb open failed!!
[0018.730] W> Failed to load kernel-dtb binary from rootfs (err=202113041)
[0018.737] I> Continue to load from partition ...
all bootloader log txt:
bootloader log.txt (46.3 KB)