Linux

• You mention this is a server VM and so you probably don't need NetworkManager or the wpa_supplicant services. If you don't wish to setup a static IP for the server VM then install and use dhcpcd instead of NetworkManager/wpa_supplicant.

• Unless you need to use WWAN (2G/3G/4G/5G) devices, you don't need ModemManager.

• Depending on your workflow, consider reducing the number of agetty instances to 1. With a single agetty instance, install and use tmux multiplexer when you need more sessions on the physical VM console.

• I don't have any experience of using seatd/elogind but I think you may be able to configure USE flags such that you only need seatd installed (i.e. don't need elogind) and since you need seatd only for running a WM occasionally, why not use seatd-launch to start the WM and not have the seatd daemon running constantly. See: https://github.com/swaywm/sway/wiki/Running-Sway-with-seatd,-elogind-or-systemd%E2%80%90logind#seatd-launch

• Lastly, the largest chunk of memory used other than the processes you can see in htop will be the Linux kernel. The Gentoo distribution kernel will have hundreds of drivers for real hardware which make no sense in a Kernel that will be used in a VM (unless you plan to use PCI/USB pass through). So, you should create a custom kernel (https://wiki.gentoo.org/wiki/Kernel/Gentoo_Kernel_Configuration_Guide) which is tailored for a KVM guest.

To do this (the following are not detailed instructions but just guidance):

• You start with "make defconfig" which creates a ".config" file with the default options from the ARCH supplied defconfig (e.g. x86_64_defconfig).
• Then you do a "make kvm_guest.config" which adds config options that makes the kernel bootable as a KVM guest.
• Next you need to do a "make filesystem.config" which will add config options for filesystems you need the kernel to support. (* see note below)
• Next you need to do a "make systemd.config" which will add config options for systemd functionality related support. (* see note below)
• Next you need to do a "make arch_x86.config" which will enable additional config options for some virtual hardware support drivers (* see note below)

Note 1: The additional "*.config" files mentioned above will need to be copied into the correct place before make will find them and I've provided some some sample config files you can use to start with below:

• https://github.com/torvalds/linux/blob/master/kernel/configs/kvm_guest.config
• https://github.com/cyano-linux/qemu-guest-kernel/blob/master/filesystem.config
• https://github.com/cyano-linux/qemu-guest-kernel/blob/master/systemd.config
• https://github.com/cyano-linux/qemu-guest-kernel/blob/master/arch_x86.config

Note 2: I'm not associated with the above github repo(cyano-linux/qemu-guest-kernel) but I have referenced it when I needed to setup a custom kernel. You can find a little documentation for the above kernel config here: https://github.com/cyano-linux/qemu-guest-kernel/blob/master/config.md