Xavier kernel building problem

Robotics & Edge Computing Jetson & Embedded Systems Jetson AGX Xavier
1

Hello,
I want to rebuild the module iwlwifi on my Xavier for wifi support. uname -r returned 4.9.140-tegra. I downloaded the source code for linux-4.9.140. I ran the commands below as root:

cd kernelbuild/linux-4.9.140 #directory of the source code
make clean
make proper
cp /lib/modules/4.9.140-tegra/build/Module.symvers ./
zcat /proc/config.gz > .config
vim .config #CONFIG_LOCALVERSION="-tegra"
vim Makefile #EXTRAVERSION = -tegra
make oldconfig
make -j8 modules_prepare
make -j8 modules
cp drivers/net/wireless/intel/iwlwifi/iwlwifi.ko /lib/modules/4.9.140-tegra/kernel/drivers/net/wireless/intel/iwlwifi/iwlwifi.ko
reboot

After rebooting the board, module iwlwifi can’t be loaded correctly, and “dmesg | grep iwl” shows:

iwlwifi: no symbol version for module_layout
iwlwifi: Unknown symbol dma_alloc_from_coherent (err 0)
iwlwifi: Unknown symbol dma_release_from_coherent (err 0)
iwlwifi: Unknown symbol debugfs_create_file (err 0)

I am new to linux, and don’t know how to deal with the problem. Can anyone help me? Thanks a lot.

2

YuzhiYang,

Could you refer to L4T document → Kernel customization and check the steps to build kernel modules?

3

Hi YuzhuYang,
Additionally you may use for reference steps from the example below that shows how to build v4l2loopback.

sudo su
cd /usr/src/linux-headers-4.9.140-tegra-ubuntu18.04_aarch64/kernel-4.9
make modules_prepare
mkdir v4l2loopback
git clone https://github.com/umlaeute/v4l2loopback.git v4l2loopback
cd v4l2loopback
make
make install
apt-get install -y v4l2loopback-dkms v4l2loopback-utils
modprobe v4l2loopback devices=1 video_nr=2 exclusive_caps=1
echo options v4l2loopback devices=1 video_nr=2 exclusive_caps=1 > /etc/modprobe.d/v4l2loopback.conf
echo v4l2loopback > /etc/modules
update-initramfs -u