Gentoo playground in qemu for development and compilation

In case you want to build some Gentoo packages on different operating system.
Could theoretically be a good package manager for an project with many dependencies.

Alternatives

• Gentoo
• Gentoo:Prefix (https://wiki.gentoo.org/wiki/Project:Prefix)

Source

https://www.gentoo.org/news/2025/02/20/gentoo-qcow2-images.html

Get qcow2 image

1. visit https://www.gentoo.org/downloads/
2. download QCOW2 disk (no root pw) [no multilib | systemd] image

Run script

#!/bin/sh

# https://distfiles.gentoo.org/releases/amd64/autobuilds/20250322T105044Z/di-amd64-console-20250322T105044Z.qcow2
version=20250322T105044Z
ssh_port=30022

# https://www.qemu.org/docs/master/system/index.html
qemu-system-x86_64 \
        -m 8G -smp 4 -cpu host -accel kvm -vga virtio -smbios type=0,uefi=on \
        -drive if=pflash,unit=0,readonly=on,file=/usr/share/edk2/OvmfX64/OVMF_CODE_4M.qcow2,format=qcow2 \
        -drive file=di-amd64-console-${version}.qcow2 \
        -net nic -net user,hostfwd=tcp::${ssh_port}-:22 \
        -name "gentoo-vm-dev" &

Log in

• root
• (no password)

Network

• guest: 10.0.2.15
• host: 10.0.2.2

SSH

1. nano /etc/ssh/sshd_config
   • PermitRootLogin yes
   • PermitEmptyPasswords yes
2. systemctl enable sshd
3. systemctl start sshd

ssh (from host): ssh -p 20022 root@localhost

TL;DR Gentoo basics

See also https://wiki.gentoo.org/wiki/Gentoo_Cheat_Sheet)

Gentoo binary packages by default

https://wiki.gentoo.org/wiki/Gentoo_Binary_Host_Quickstart

1. nano /etc/portage/make.conf
   • FEATURES="getbinpkg"
2. getuto
   • note: may take a while

NOTE: some binary packages may not meet current USE flags requirements. e.g.:

!!! The following binary packages have been ignored due to non matching USE:

    =net-libs/nghttp2-1.65.0-r1 -systemd
    =net-libs/nghttp2-1.65.0-r1 -systemd xml
    =net-libs/nghttp2-1.65.0-r1 xml

To fix this just add desired flags to package override.

• nano /etc/portage/package.use/my-binpkg-flags
  • net-libs/nghttp2 xml

Installing packages

1. emerge --sync -q - sync portage and overlays
2. emerge -uUD world -vp - update all packages (optional)
3. emerge app-portage/eix app-shells/gentoo-bashcomp -q
4. eix-update - update eix database

Searching packages

• by name: eix something
• by description: eix -S something
• compact list: eix -c -I something_installed

Using multilib (abi_x86_32 support)

1. eselect profile list
   • this will show available profiles, current no-multilib profile marked with *
2. eselect profile set 22
   • this will set multilib profile similar to currently used one
3. emerge -1 sys-kernel/gentoo-kernel binutils util-linux -q
   • just in case
4. nano /etc/portage/package.use/my-multilib
   • sys-libs/ncurses abi_x86_32
   • then emerge -1 sys-libs/ncurses -q

Using overlays

https://wiki.gentoo.org/wiki/Eselect/Repository

1. emerge app-eselect/eselect-repository -q
2. eselect repository add test git https://github.com/test/test.git
3. emaint sync -r test
4. eix -c --in-overlay test - just for example
5. nano /etc/portage/package.accept_keywords/my-unstable-pkgs
   • To use unstable or unkeyworded packages:
     • for unstable just add package name: dev-util/test-pkgname::test or =dev-util/test-pkgname-1.2.3::test
     • for unkeyworded and 9999 add ** at the end: dev-util/test-pkgname::test **
6. nano /etc/portage/package.use/my-multilib
   • dev-util/test-pkgname::test abi_x86_32 - if you also want 32bit support
7. emerge dev-util/test-pkgname::test -q

Get package from installed one

1. quickpkg dev-util/test-pkgname
2. use e.g. rsync to download it on host from /var/cache/binpkgs/dev-util/test-pkgname/*
   • rsync -r -e 'ssh -p 20022' root@localhost:/var/cache/binpkgs/dev-util/test-pkgname/* .
3. repeat with package dependencies if needed