What is linux-firmware when updating kernel?

Question

When doing yum install kernel

It shows two packages:

kernel
linux-firmware

What is the linux-firmware here?

Answer 1

From https://wiki.ubuntu.com/Kernel/Firmware :

Many devices have two essential software pieces that make them function in your operating system. The first is a working driver, which is the software that lets your system talk to the hardware. The second is firmware, which is usually a small piece of code that is uploaded directly to the device for it to function correctly. You can think of the firmware as a way of programming the hardware inside the device. In fact, in almost all cases firmware is treated like hardware in that it's a black box; there's no accompanying source code that is freely distributed with it.

While many devices can work without firmware, many more complicated ones require firmware to be properly set up, e.g. almost all modern GPUs, CPUs (microcode updates which fix bugs, erratas and vulnerabilities), Ethernet cards and WiFi adapters/phone radio modules (e.g. there's a ton of variability in terms of properly broadcasting and receiving wireless signal and there are regional limitations as well), SCSI/RAID adapters, multimedia devices including webcams, etc.

Some people choose not to use firmware because they believe it can be used to extend hardware capabilities beyond what was initially designed/built into them, check Linux-libre So, if you have a server or a relatively old PC/laptop you can try running without firmware or even use the Linux-Libre kernel. I don't share this point of view because modern hardware already has ROM and its circuitry is in absolute most cases "closed" sourced, so it's not obvious whether it's backdoor-free in the first place.

This package contains not just single firmware, it contains multiple files for various hardware devices (some devices require multiple files). Like I said, if everything works for you, you may as well never install it.