[tareqak]

I guess situation where you are privacy-conscious enough to inspect all the source code up to and including the CPU microcode? There was post in this thread about FreeBSD being available. If there is a Linux kernel for it, then a distribution might be not too far off e.g. Gentoo (I’m not aware of any POWER9 Linux distribution as off yet).

[boudin]

There's a PPC handbook for Gentoo:

https://wiki.gentoo.org/wiki/Handbook:PPC

Looking around, power9 seems to work fine. For software compatibility it's more a case by case scenario.

[classichasclass]

Fedora 28 and up boots directly on the Talos II and should boot on this. I use F28 myself, but the Raptor folks use Debian which I'm told also works well.

[nicoburns]

Looks like Debian supports POWER9 https://wiki.debian.org/PPC64