Contribute back how and where? Definitely not to Gentoo if we look at the meagre numbers here.

Red Hat contributes to a broad spectrum of Linux packages, drivers, and of course the kernel itself [1].

One example is virtualization: the virtio stack is maintained by Red Hat (afaik). This is a huge driver behind the “democratization” of virtualization in general, allowing users and small companies to access performant virt without selling a kidney to VMware.

Also, Red Hat contributes to or maintains all of the components involved in OpenShift and OpenStack (one of which is virtio!).

[1] https://lwn.net/Articles/915435/

Why should Red Hat be expected to contribute to Gentoo? A distro is funded by its own users. What distro directly contributes to another distro if it’s not a derivative or something?

Red Hat primarily contributes code to the kernel and various OSS projects, paid for by the clients on enterprise contracts. A paying client needs something and it gets done. Then the rest of us get to benefit by receiving the code for free. It’s a beautiful model.

If you look at lists of top contributors, Red Hat (along with the usual suspects in enterprise) are consistently at the top.

Presumably, contribute to the entire ecosystem in terms of package maintenance and other non-monetary forms.

As others mentioned, Red Hat (and SUSE) has been amazing for the overall Linux community. They give back far more than what the GPL requires them to. Nearly every one of their paid "enterprise" products has a completely free and open source version.

For example:

  - Red Hat Identity Management -> FreeIPA  (i.e. Active Directory for Linux)
  - Red Hat Satellite -> The Foreman + Katello
  - Ansible ... Ansible.
  - Red Hat OpenShift -> OKD
  - And more I'm not going to list.

Red Hat employs a significant number of GCC core devs.

Red Hat contributes a huge amount to the open source ecosystem. They're one of the biggest contributors to the Linux kernel (maybe the biggest).