I’m trying to build a NixOS system image on x86_64-linux using this flake.nix:
{
inputs.nixpkgs.url = "github:nixos/nixpkgs?ref=nixos-unstable";
outputs = { self, nixpkgs }: {
packages.x86_64-linux.default = self.nixosConfigurations.image.config.system.build.images.raw-efi;
nixosConfigurations.image = nixpkgs.lib.nixosSystem {
modules = [ { nixpkgs.hostPlatform.system = "aarch64-linux"; } ];
};
};
}
It works fine when nixpkgs.hostPlatform.system is set to x86_64-linux — the expected .img file is produced. However, after I added boot.binfmt.emulatedSystems = [ "aarch64-linux" ] in my /etc/nixos/configuration.nix and switched nixpkgs.hostPlatform.system to aarch64-linux, running nix build -L . spews out a large number of errors like:
nixos-disk-image> copying path '/nix/store/7llyx0szys4k1jaapd6jjcf0j3lcfdb3-systemd-boot' to 'local'...
nixos-disk-image> copying path '/nix/store/09g7m9vpkdyq3hr7q4kzd03qif0dcy2i-install-systemd-boot.sh' to 'local'...
nixos-disk-image> copying path '/nix/store/dkkdq2ym3yzlb2njdlyl6byn2n6zhalp-unit-script-growpart-start' to 'local'...
nixos-disk-image> copying path '/nix/store/lmvdaqsksx3mjgzwpyr9k57h3c47b98h-unit-growpart.service' to 'local'...
nixos-disk-image> copying path '/nix/store/zjwppzaqfsd42q43sgycvicfn2p5vm2i-system-path' to 'local'...
nixos-disk-image> copying path '/nix/store/smp2h6wk109sbq2g0dnap1rx589ws36k-linux-6.18.40-modules' to 'local'...
nixos-disk-image> copying path '/nix/store/ky5266j9ykiqjx1yjf41ls5xx1dgfy6p-dbus-1' to 'local'...
nixos-disk-image> copying path '/nix/store/l0vij21k3kcpjz35ywi73hqr42cv1m34-X-Restart-Triggers-dbus-broker' to 'local'...
nixos-disk-image> copying path '/nix/store/ymmpsfcix67fbqn9g8694hrfh300wjc3-unit-dbus-broker.service' to 'local'...
nixos-disk-image> copying path '/nix/store/knc30s8r3r9i9n2jsksb8ak4v1hf0yi8-unit-dbus-broker.service' to 'local'...
nixos-disk-image> copying path '/nix/store/d4i4m5jw8f5sxr7jrq8mpw8jkdldklb9-user-units' to 'local'...
nixos-disk-image> copying path '/nix/store/8ss4mciz3vi1dvwlw560qiw3908fp0yw-system-units' to 'local'...
nixos-disk-image> copying path '/nix/store/vhlmqq8abvyx32srx8rb6njmvjkjfc3r-etc-nix-registry.json' to 'local'...
nixos-disk-image> copying path '/nix/store/gzhmlmziv9w0glpmhm19pvrv4iqmvz9p-etc' to 'local'...
nixos-disk-image> copying path '/nix/store/kpybhr610ym3b13lfjpqbv6pnyfyaaa1-nixos-system-nixos-efi-raw-26.11.20260726.624af66' to 'local'...
nixos-disk-image> installation finished!
nixos-disk-image> Automatic disk size...
nixos-disk-image> Closure space use: 4129173504 bytes
nixos-disk-image> fudge: 214717022 bytes
nixos-disk-image> Filesystem size needed: 4343894016 bytes
nixos-disk-image> Additional space: 806372352 bytes
nixos-disk-image> Disk image size: 5150605312 bytes
nixos-disk-image> Model: (file)
nixos-disk-image> Disk /build/nixos.raw: 5151MB
nixos-disk-image> Sector size (logical/physical): 512B/512B
nixos-disk-image> Partition Table: gpt
nixos-disk-image> Disk Flags:
nixos-disk-image>
nixos-disk-image> Number Start End Size File system Name Flags
nixos-disk-image> 1 8389kB 269MB 261MB fat32 ESP boot, esp
nixos-disk-image> 2 269MB 5150MB 4880MB ext4 primary
nixos-disk-image>
nixos-disk-image> Warning: The kernel is still using the old partition table.
nixos-disk-image> The new table will be used at the next reboot or after you
nixos-disk-image> run partprobe(8) or kpartx(8)
nixos-disk-image> The operation has completed successfully.
nixos-disk-image> mke2fs 1.47.4 (6-Mar-2025)
nixos-disk-image> Discarding device blocks: done
nixos-disk-image> Creating filesystem with 1191424 4k blocks and 298368 inodes
nixos-disk-image> Filesystem UUID: 2a3889c9-9f48-4182-9134-98c9e572b234
nixos-disk-image> Superblock backups stored on blocks:
nixos-disk-image> 32768, 98304, 163840, 229376, 294912, 819200, 884736
nixos-disk-image>
nixos-disk-image> Allocating group tables: done
nixos-disk-image> Writing inode tables: done
nixos-disk-image> Creating journal (16384 blocks): done
nixos-disk-image> Writing superblocks and filesystem accounting information: done
nixos-disk-image>
nixos-disk-image> copying staging root to image...
nixos-disk-image> [ 0.000000] Linux version 6.6.0 (nixbld@localhost) (gcc (GCC) 15.3.0, GNU ld (GNU Binutils) 2.46) #1 Sat Jul 18 01:32:10 UTC 2026
nixos-disk-image> [ 0.000000] memblock address range: 0x7fffd5c00000 - 0x7fffdc000000
nixos-disk-image> [ 0.000000] Zone ranges:
nixos-disk-image> [ 0.000000] Normal [mem 0x00007fffd5c00000-0x00007fffdbffffff]
nixos-disk-image> [ 0.000000] Movable zone start for each node
nixos-disk-image> [ 0.000000] Early memory node ranges
nixos-disk-image> [ 0.000000] node 0: [mem 0x00007fffd5c00000-0x00007fffdbffffff]
nixos-disk-image> [ 0.000000] Initmem setup node 0 [mem 0x00007fffd5c00000-0x00007fffdbffffff]
nixos-disk-image> [ 0.000000] Kernel command line: mem=100M virtio_mmio.device=352@0x1000000:1
nixos-disk-image> [ 0.000000] Dentry cache hash table entries: 16384 (order: 5, 131072 bytes, linear)
nixos-disk-image> [ 0.000000] Inode-cache hash table entries: 8192 (order: 4, 65536 bytes, linear)
nixos-disk-image> [ 0.000000] Built 1 zonelists, mobility grouping on. Total pages: 25250
nixos-disk-image> [ 0.000000] mem auto-init: stack:all(zero), heap alloc:off, heap free:off
nixos-disk-image> [ 0.000000] Memory: 100768K/102400K available (6898K kernel code, 1663K rwdata, 1564K rodata, 139K init, 337K bss, 1632K reserved, 0K cma-reserved)
nixos-disk-image> [ 0.000000] SLUB: HWalign=32, Order=0-3, MinObjects=0, CPUs=1, Nodes=1
nixos-disk-image> [ 0.000000] trace event string verifier disabled
nixos-disk-image> [ 0.000000] NR_IRQS: 4096
nixos-disk-image> [ 0.000000] lkl: irqs initialized
nixos-disk-image> [ 0.000000] clocksource: lkl: mask: 0xffffffffffffffff max_cycles: 0x1cd42e4dffb, max_idle_ns: 881590591483 ns
nixos-disk-image> [ 0.000029] lkl: time and timers initialized (irq2)
nixos-disk-image> [ 0.001607] pid_max: default: 4096 minimum: 301
nixos-disk-image> [ 0.005436] Mount-cache hash table entries: 512 (order: 0, 4096 bytes, linear)
nixos-disk-image> [ 0.005534] Mountpoint-cache hash table entries: 512 (order: 0, 4096 bytes, linear)
nixos-disk-image> [ 0.094996] printk: console [lkl_console0] enabled
nixos-disk-image> [ 0.097354] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 19112604462750000 ns
nixos-disk-image> [ 0.101053] NET: Registered PF_NETLINK/PF_ROUTE protocol family
nixos-disk-image> [ 0.107371] lkl_pci: probe of lkl_pci failed with error -1
nixos-disk-image> [ 0.270921] raid6: skipped pq benchmark and selected int64x8
nixos-disk-image> [ 0.271032] raid6: using intx1 recovery algorithm
nixos-disk-image> [ 0.288161] vgaarb: loaded
nixos-disk-image> [ 0.289600] clocksource: Switched to clocksource lkl
nixos-disk-image> [ 0.324391] NET: Registered PF_INET protocol family
nixos-disk-image> [ 0.326614] IP idents hash table entries: 2048 (order: 2, 16384 bytes, linear)
nixos-disk-image> [ 0.332062] tcp_listen_portaddr_hash hash table entries: 512 (order: 0, 4096 bytes, linear)
nixos-disk-image> [ 0.332607] Table-perturb hash table entries: 65536 (order: 6, 262144 bytes, linear)
nixos-disk-image> [ 0.332844] TCP established hash table entries: 1024 (order: 1, 8192 bytes, linear)
nixos-disk-image> [ 0.333539] TCP bind hash table entries: 1024 (order: 2, 16384 bytes, linear)
nixos-disk-image> [ 0.333878] TCP: Hash tables configured (established 1024 bind 1024)
nixos-disk-image> [ 0.336279] UDP hash table entries: 128 (order: 0, 4096 bytes, linear)
nixos-disk-image> [ 0.336644] UDP-Lite hash table entries: 128 (order: 0, 4096 bytes, linear)
nixos-disk-image> [ 0.338863] PCI: CLS 0 bytes, default 32
nixos-disk-image> [ 0.343990] virtio-mmio: Registering device virtio-mmio.0 at 0x1000000-0x100015f, IRQ 1.
nixos-disk-image> [ 0.385141] workingset: timestamp_bits=62 max_order=15 bucket_order=0
nixos-disk-image> [ 0.390314] SGI XFS with ACLs, security attributes, no debug enabled
nixos-disk-image> [ 0.400101] xor: automatically using best checksumming function 8regs
nixos-disk-image> [ 0.400616] io scheduler mq-deadline registered
nixos-disk-image> [ 0.400854] io scheduler kyber registered
nixos-disk-image> [ 0.462964] virtio_blk virtio0: 1/0/0 default/read/poll queues
nixos-disk-image> [ 0.471426] virtio_blk virtio0: [vda] 10059776 512-byte logical blocks (5.15 GB/4.80 GiB)
nixos-disk-image> [ 0.561423] vda: vda1 vda2
nixos-disk-image> [ 0.584076] NET: Registered PF_INET6 protocol family
nixos-disk-image> [ 0.597999] Segment Routing with IPv6
nixos-disk-image> [ 0.598391] In-situ OAM (IOAM) with IPv6
nixos-disk-image> [ 0.599172] sit: IPv6, IPv4 and MPLS over IPv4 tunneling driver
nixos-disk-image> [ 0.694428] Btrfs loaded, zoned=no, fsverity=no
nixos-disk-image> [ 0.700489] Warning: unable to open an initial console.
nixos-disk-image> [ 0.701345] This architecture does not have kernel memory protection.
nixos-disk-image> [ 0.701591] Run /init as init process
nixos-disk-image> [ 0.838581] EXT4-fs (vda2): mounted filesystem 2a3889c9-9f48-4182-9134-98c9e572b234 r/w with ordered data mode. Quota mode: disabled.
nixos-disk-image> error while reading directory /build/root/etc: Cannot allocate memory
nixos-disk-image> error while reading directory /build/root: Cannot allocate memory
nixos-disk-image> error while reading directory /build/root/nix/var/nix/db: Cannot allocate memory
nixos-disk-image> error while reading directory /build/root/nix/var/nix/temproots: Cannot allocate memory
nixos-disk-image> error while reading directory /build/root/nix/var/nix/gcroots/auto: Cannot allocate memory
nixos-disk-image> error while reading directory /build/root/nix/var/nix/gcroots/per-user: Cannot allocate memory
nixos-disk-image> error while reading directory /build/root/nix/var/nix/gcroots: Cannot allocate memory
nixos-disk-image> error while reading directory /build/root/nix/var/nix/profiles/per-user/root: Cannot allocate memory
nixos-disk-image> error while reading directory /build/root/nix/var/nix/profiles/per-user: Cannot allocate memory
nixos-disk-image> error while reading directory /build/root/nix/var/nix/profiles: Cannot allocate memory
nixos-disk-image> error while reading directory /build/root/nix/var/nix: Cannot allocate memory
nixos-disk-image> error while reading directory /build/root/nix/var: Cannot allocate memory
nixos-disk-image> error while reading directory /build/root/nix/store/z6b3si9n21mqaapyjbwfhckhw98yz7np-shadow-4.19.4/lib: Cannot allocate memory
nixos-disk-image> error while reading directory /build/root/nix/store/z6b3si9n21mqaapyjbwfhckhw98yz7np-shadow-4.19.4/bin: Cannot allocate memory
nixos-disk-image> error while reading directory /build/root/nix/store/z6b3si9n21mqaapyjbwfhckhw98yz7np-shadow-4.19.4/share/locale/pl/LC_MESSAGES: Cannot allocate memory
nixos-disk-image> error while reading directory /build/root/nix/store/z6b3si9n21mqaapyjbwfhckhw98yz7np-shadow-4.19.4/share/locale/pl: Cannot allocate memory
nixos-disk-image> error while reading directory /build/root/nix/store/z6b3si9n21mqaapyjbwfhckhw98yz7np-shadow-4.19.4/share/locale/nl/LC_MESSAGES: Cannot allocate memory
nixos-disk-image> error while reading directory /build/root/nix/store/z6b3si9n21mqaapyjbwfhckhw98yz7np-shadow-4.19.4/share/locale/nl: Cannot allocate memory
nixos-disk-image> error while reading directory /build/root/nix/store/z6b3si9n21mqaapyjbwfhckhw98yz7np-shadow-4.19.4/share/locale/ka/LC_MESSAGES: Cannot allocate memory
...
My machine still has plenty of free memory. Any idea what’s going on and how to fix this?
