Run 'emerge -1 net-misc/spice-gtk' and you'll get results like that shown in the attached buid.log file. The key error is this: "meson.build:43:0: ERROR: Subproject exists but has no meson.build file" I jumped onto my other computer which has Gentoo installed and saw that they're using the same version of spice-gtk. Virt-manager works fine on that machine, so I decided to do some digging, since I have a working example at my disposal. I unpacked the tarball and ran 'tree' against the directory created in /var/tmp/portage. See attached gentoo-tree-output.txt file. I did the same same on my Funtoo machine. See attached funtoo-tree-output.txt file. If you scroll down to the subprojects directory for each one, you'll see that the Funtoo version has quite a few files missing, to include the meson build file that Portage is complaining about. I then compared the ebuilds for each machine. The SRC_URI values are different. Funtoo pulls from their gitlab repo while Gentoo pulls from their regular website. So I decided to mod the ebuild to see if using Gentoo's SRC_URI value would make the build work. I commented out the original SRC_URI value and added a new one to match what Gentoo was using. I also commented out the 'S=' line. See attached modded-ebuild.txt file. With the mods in place, I ran ran 'ebuild clean merge' against the ebuild and the package installed without a hitch. Now that I had that final dependency in place, I was able to install virt-manager. After a little configuration, I was able to connect to my server and pull up a session on a Gentoo VM I have on it. Everything worked as expected. See the attached virt-manager.png file.