Unable to get the right Linux kernel headers to build a kernel module

2
votes

I am trying to build a sample Linux kernel module using the following command in my makefile on my Raspberry Pi 3B+ running the latest Raspbian Buster OS updated with sudo apt-get dist-upgrade:

make -C /lib/modules/$(shell uname -r)/build/ M=$(PWD) modules

I get the following output:

make -C /lib/modules/4.19.57-v7+/build/ M=/home/pi/isr_test modules
make[1]: *** /lib/modules/4.19.57-v7+/build/: No such file or directory.  Stop.
make: *** [Makefile:4: all] Error 2

I tried installing linux headers using this command:

sudo apt-get install linux-headers-$(uname -r)
Reading package lists... Done
Building dependency tree
Reading state information... Done
E: Unable to locate package linux-headers-4.19.57-v7
E: Couldn't find any package by glob 'linux-headers-4.19.57-v7'
E: Couldn't find any package by regex 'linux-headers-4.19.57-v7'

I tried looking for Linux headers using this command, and it looks like they are installed:

dpkg -l | grep kernel-headers
ii  raspberrypi-kernel-headers            1.20190718-1                          armhf        Header files for the Raspberry Pi Linux kernel

I tried looking in the /lib/modules directory:

ls /lib/modules
4.19.58+  4.19.58-v7+  4.19.58-v7l+

See how there's no 4.19.57 there?

Also, under /usr/src, all I have is these directories:

ls /usr/src
linux-headers-4.19.58+  linux-headers-4.19.58-v7+  linux-headers-4.19.58-v7l+  sense-hat

Again, nothing for 4.19.57.

For the current OS, here's what I get when I run uname -r:

uname -r
4.19.57-v7+

When I change my makefile to point to the 4.19.58-v7+ instead of 4.19.57-v7+, I get my module to build with no issues.

I'm expecting to see folders with 4.19.57 in their names, but all I get is 4.19.58 (see the folders above). How can I get the Linux header files that match my Linux kernel version? Or does it not matter?

1
clinuxlinux-kernelraspberry-pi3header-files
Reboot your machine and choose new kernel in the boot loader. It seems you updated kernel without rebooting. Possible variants: distribution wrongly provided updates, update has been broken. - 0andriy
Debian/Raspbian's APT doesn't usually automatically remove packages related to the running kernel, although that doesn't prevent them being marked as obsolete packages. The mechanics of this are that the packages get listed in an APT::NeverAutoRemove section in the "/etc/apt/apt.conf.d/01autoremove-kernels" file, which is updated by the kernel postinstall script "/etc/kernel/postinst.d/apt-auto-removal". - Ian Abbott

1 Answers

2
votes

Turns out, all I had to do was to reboot my Raspberry Pi after updating the OS. Now it's at 4.19.58, and all the headers match the OS version and everything compiles just fine.