Re: [PATCH 1/7] host/rootfs: Use full util-linux and systemd

[Demi Marie Obenour <demiobenour@gmail.com>]

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On 10/29/25 07:36, Alyssa Ross wrote:
> Demi Marie Obenour <demiobenour@gmail.com> writes:
> 
>> Busybox provides a broken fdisk that doesn't support GPT, only MBR.
>> The systemd built against musl doesn't include systemd-pull, so
>> systemd-sysupdate doesn't work.  Therefore, use all of util-linux's
>> command-line tools, and use systemd built against glibc.
> 
> That's a problem that's going to need to be fixed.  We're not mixing two
> different libcs on the host.

Unfortunately, systemd-pull can't be built with musl libc.  That leaves
four options:

1. Try to fix the build problem, knowing that it could come back.
2. Mix two libcs on the host.
3. Try to fix the build (but this could take quite a while to upstream).
4. Use glibc on the host.

I don't think we should ship with option 2, but I think it might be
acceptable until the underlying problem is solved.

>> Signed-off-by: Demi Marie Obenour <demiobenour@gmail.com>
>> ---
>>  host/rootfs/default.nix | 43 ++++++++++++++++++-------------------------
>>  1 file changed, 18 insertions(+), 25 deletions(-)
> 
> Okay idea overall.  I like the idea of less busybox.  Busybox →
> util-linux should probably be a patch of its own.

Will fix in v2.

>> diff --git a/host/rootfs/default.nix b/host/rootfs/default.nix
>> index 0d79f7ca54ccc86eb0fa6e743f2011237d365f24..00052222507077b9e94a5ed0a3fbddd27caeefc3 100644
>> --- a/host/rootfs/default.nix
>> +++ b/host/rootfs/default.nix
>> @@ -4,20 +4,20 @@
>>  
>>  import ../../lib/call-package.nix (
>>  { callSpectrumPackage, spectrum-build-tools, src
>> -, pkgsMusl, pkgsStatic, linux_latest
>> +, pkgsMusl, pkgsStatic, linux_latest, systemd
>>  }:
>>  pkgsStatic.callPackage (
>>  
>>  { busybox, cloud-hypervisor, cryptsetup, dbus, erofs-utils, execline
>>  , inkscape, inotify-tools, iproute2, jq, lib, mdevd, nixos
>>  , runCommand, s6, s6-linux-init, s6-rc, socat, spectrum-host-tools
>> -, stdenvNoCC, util-linuxMinimal, virtiofsd, writeClosure
>> +, stdenvNoCC, util-linux, virtiofsd, writeClosure
> 
>   util-linuxMinimal = util-linux.override {
>     cryptsetupSupport = false;
>     nlsSupport = false;
>     ncursesSupport = false;
>     pamSupport = false;
>     shadowSupport = false;
>     systemdSupport = false;
>     translateManpages = false;
>   };
> 
> So how come we need the non-minimal version?

I didn't check.

>>      # Weston doesn't support SVG icons.
>>      inkscape -w 20 -h 20 \
>>          -o $out/usr/share/icons/hicolor/20x20/apps/com.system76.CosmicFiles.png \
>>          ${cosmic-files}/share/icons/hicolor/24x24/apps/com.system76.CosmicFiles.svg
>>  
>> -    ln -st $out/usr/bin \
>> -        ${concatMapStringsSep " " (p: "${p}/bin/*") packages} \
>> -        ${xdg-desktop-portal}/libexec/xdg-document-portal \
>> -        ${xdg-desktop-portal-gtk}/libexec/xdg-desktop-portal-gtk
>> +    ln -sft "$out/usr/bin" \
>> +        ${concatMapStringsSep " " (p: "${escapeShellArg p}/bin/*") packages} \
>> +        ${escapeShellArg xdg-desktop-portal}/libexec/xdg-document-portal \
>> +        ${escapeShellArg xdg-desktop-portal-gtk}/libexec/xdg-desktop-portal-gtk
>>      ln -st $out/usr/share/dbus-1 \
>> -        ${dbus}/share/dbus-1/session.conf
>> +        ${escapeShellArg dbus}/share/dbus-1/session.conf
>>      ln -st $out/usr/share/dbus-1/services \
>> -        ${xdg-desktop-portal-gtk}/share/dbus-1/services/org.freedesktop.impl.portal.desktop.gtk.service
>> -
>> -    for pkg in ${escapeShellArgs usrPackages}; do
>> -        lndir -ignorelinks -silent "$pkg" "$out/usr"
>> -    done
>> +        ${escapeShellArg xdg-desktop-portal-gtk}/share/dbus-1/services/org.freedesktop.impl.portal.desktop.gtk.service
> 
> Unrelated changes.  We don't need to escape Nix store paths, because we
> rely on Nixpkgs, which would break if store paths had weird characters
> in them.

Will drop in v2.

>> +    # clobber any conflicting files from busybox
>> +    ln -sft "$out/usr/bin" ${escapeShellArg util-linux}/bin/*
> 
> The approach we've taken so far is to disable those tools in Busybox,
> and avoid conflicting symlinks, and I like that better.  Alternatively,
> if you want to figure out which Busybox tools are actually needed, we
> could switch to a minimal build and enable only what we use.

I don't want to block on either of those, and I'd rather not risk
breaking the build whenever util-linux adds a new tool.  It's pretty
clear that util-linux is to be preferred over Busybox in the event
of a conflict.

This does add bloat, but there are far *more* sources of bloat right
now, so I think that should be part of a more general debloating
effort.

>>      ${concatStrings (mapAttrsToList (name: path: ''
>>        ln -s ${path} $out/usr/lib/spectrum/vm/${name}
>>      '') appvms)}
>> -
>> -    # TODO: this is a hack and we should just build the util-linux
>> -    # programs we want.
>> -    # https://lore.kernel.org/util-linux/87zgrl6ufb.fsf@alyssa.is/
>> -    ln -s ${util-linuxMinimal}/bin/{findfs,uuidgen,lsblk,mount} $out/usr/bin
>> -
>> -    # TODO: this is another hack and it should be possible
>> -    # to build systemd without this.
>> -    ln -s -- ${lib.escapeShellArg systemd}/bin/udevadm "$out/usr/bin"
>>    '';
>>  in
>>  
>>
>> -- 
>> 2.51.2
-- 
Sincerely,
Demi Marie Obenour (she/her/hers)


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