What is 'linux-libc-dev'? "Linux kernel headers for development" for another kernel series in software updater

Solution 1:

The linux-libc-dev package contains headers of user-space libraries.

In Ubuntu LTS releases they are not upgraded with the HWE kernels.

It is normal, and you don't need to change it.

The Linux headers are in another package called linux-headers... that does match the kernel version.

See apt-cache show linux-libc-dev

Linux Kernel Headers for development
 This package provides headers from the Linux kernel.  These headers
 are used by the installed headers for GNU glibc and other system
 libraries. They are NOT meant to be used to build third-party modules for
 your kernel. Use linux-headers-* packages for that.

Almost exactly what I wrote before ;-)