buildInLinuxVM: switch from 9p to virtiofs (#362081)

, img ? pkgs.stdenv.hostPlatform.linux-kernel.target

, storeDir ? builtins.storeDir

, rootModules ?

    [ "virtio_pci" "virtio_mmio" "virtio_blk" "virtio_balloon" "virtio_rng" "ext4" "unix" "9p" "9pnet_virtio" "crc32c_generic" ]

    [ "virtio_pci" "virtio_mmio" "virtio_blk" "virtio_balloon" "virtio_rng" "ext4" "unix" "virtiofs" "crc32c_generic" ]

}:

let

    echo "mounting Nix store..."

    mkdir -p /fs${storeDir}

    mount -t 9p store /fs${storeDir} -o trans=virtio,version=9p2000.L,cache=loose,msize=131072

    mount -t virtiofs store /fs${storeDir}

    mkdir -p /fs/tmp /fs/run /fs/var

    mount -t tmpfs -o "mode=1777" none /fs/tmp

    echo "mounting host's temporary directory..."

    mkdir -p /fs/tmp/xchg

    mount -t 9p xchg /fs/tmp/xchg -o trans=virtio,version=9p2000.L,msize=131072

    mount -t virtiofs xchg /fs/tmp/xchg

    mkdir -p /fs/proc

    mount -t proc none /fs/proc

    ${if (customQemu != null) then customQemu else (qemu-common.qemuBinary qemu)} \

      -nographic -no-reboot \

      -device virtio-rng-pci \

      -virtfs local,path=${storeDir},security_model=none,mount_tag=store \

      -virtfs local,path=xchg,security_model=none,mount_tag=xchg \

      -chardev socket,id=store,path=virtio-store.sock \

      -device vhost-user-fs-pci,chardev=store,tag=store \

      -chardev socket,id=xchg,path=virtio-xchg.sock \

      -device vhost-user-fs-pci,chardev=xchg,tag=xchg \

      ''${diskImage:+-drive file=$diskImage,if=virtio,cache=unsafe,werror=report} \

      -kernel ${kernel}/${img} \

      -initrd ${initrd}/initrd \

    cat > ./run-vm <<EOF

    #! ${bash}/bin/sh

    ''${diskImage:+diskImage=$diskImage}

    ${pkgs.virtiofsd}/bin/virtiofsd --xattr --socket-path virtio-store.sock --sandbox none --shared-dir "${storeDir}" &

    ${pkgs.virtiofsd}/bin/virtiofsd --xattr --socket-path virtio-xchg.sock --sandbox none --shared-dir xchg &

    ${qemuCommand}

    EOF

    args = ["-e" (vmRunCommand qemuCommandLinux)];

    origArgs = args;

    origBuilder = builder;

    QEMU_OPTS = "${QEMU_OPTS} -m ${toString memSize}";

    QEMU_OPTS = "${QEMU_OPTS} -m ${toString memSize} -object memory-backend-memfd,id=mem,size=${toString memSize}M,share=on -machine memory-backend=mem";

    passAsFile = []; # HACK fix - see https://github.com/NixOS/nixpkgs/issues/16742

  });