tvl-depot/tvix/boot/default.nix

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{ lib, pkgs, ... }:
rec {
# A binary that sets up /nix/store from virtiofs, lists all store paths, and
# powers off the machine.
tvix-init = pkgs.buildGoModule rec {
name = "tvix-init";
src = lib.fileset.toSource {
root = ./.;
fileset = ./tvix-init.go;
};
vendorHash = null;
postPatch = "go mod init ${name}";
};
# A kernel with virtiofs support baked in
# TODO: make a smaller kernel, we don't need a gazillion filesystems and
# device drivers in it.
kernel = pkgs.buildLinux ({ } // {
inherit (pkgs.linuxPackages_latest.kernel) src version modDirVersion;
autoModules = false;
kernelPreferBuiltin = true;
ignoreConfigErrors = true;
kernelPatches = [ ];
structuredExtraConfig = with pkgs.lib.kernel; {
FUSE_FS = option yes;
DAX_DRIVER = option yes;
DAX = option yes;
FS_DAX = option yes;
VIRTIO_FS = option yes;
VIRTIO = option yes;
ZONE_DEVICE = option yes;
};
});
# A build framework for minimal initrds
uroot = pkgs.buildGoModule rec {
pname = "u-root";
version = "0.14.0";
src = pkgs.fetchFromGitHub {
owner = "u-root";
repo = "u-root";
rev = "v${version}";
hash = "sha256-8zA3pHf45MdUcq/MA/mf0KCTxB1viHieU/oigYwIPgo=";
};
vendorHash = null;
doCheck = false; # Some tests invoke /bin/bash
};
# Use u-root to build a initrd with our tvix-init inside.
initrd = pkgs.stdenv.mkDerivation {
name = "initrd.cpio";
nativeBuildInputs = [ pkgs.go ];
# https://github.com/u-root/u-root/issues/2466
buildCommand = ''
mkdir -p /tmp/go/src/github.com/u-root/
cp -R ${uroot.src} /tmp/go/src/github.com/u-root/u-root
cd /tmp/go/src/github.com/u-root/u-root
chmod +w .
cp ${tvix-init}/bin/tvix-init tvix-init
export HOME=$(mktemp -d)
export GOROOT="$(go env GOROOT)"
GO111MODULE=off GOPATH=/tmp/go GOPROXY=off ${uroot}/bin/u-root -files ./tvix-init -initcmd "/tvix-init" -o $out
'';
};
# Start a `tvix-store` virtiofs daemon from $PATH, then a cloud-hypervisor
# pointed to it.
# Supports the following env vars (and defaults)
# CH_NUM_CPUS=2
# CH_MEM_SIZE=512M
# CH_CMDLINE=""
runVM = pkgs.writers.writeBashBin "run-tvix-vm" ''
tempdir=$(mktemp -d)
cleanup() {
kill $virtiofsd_pid
if [[ -n ''${work_dir-} ]]; then
chmod -R u+rw "$tempdir"
rm -rf "$tempdir"
fi
}
trap cleanup EXIT
# Spin up the virtiofs daemon
tvix-store --otlp=false virtiofs -l $tempdir/tvix.sock &
virtiofsd_pid=$!
# Wait for the socket to exist.
until [ -e $tempdir/tvix.sock ]; do sleep 0.1; done
CH_NUM_CPUS="''${CH_NUM_CPUS:-2}"
CH_MEM_SIZE="''${CH_MEM_SIZE:-512M}"
CH_CMDLINE="''${CH_CMDLINE:-}"
# spin up cloud_hypervisor
${pkgs.cloud-hypervisor}/bin/cloud-hypervisor \
--cpus boot=$CH_NUM_CPU \
--memory mergeable=on,shared=on,size=$CH_MEM_SIZE \
--console null \
--serial tty \
--kernel ${kernel}/${pkgs.stdenv.hostPlatform.linux-kernel.target} \
--initramfs ${initrd} \
--cmdline "console=ttyS0 $CH_CMDLINE" \
--fs tag=tvix,socket=$tempdir/tvix.sock,num_queues=''${CH_NUM_CPU},queue_size=512
'';
meta.ci.targets = [
"initrd"
"kernel"
"runVM"
];
}