From mboxrd@z Thu Jan  1 00:00:00 1970
From: ludo@gnu.org (Ludovic =?utf-8?Q?Court=C3=A8s?=)
Subject: Re: libvirt with modified QEMU and OVMF
Date: Sat, 08 Sep 2018 13:22:37 +0200
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References: <129c5140-eb4c-27df-fe43-6f7cbd423edd@larf.space>
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In-Reply-To: <129c5140-eb4c-27df-fe43-6f7cbd423edd@larf.space> ("Lars
	\=\?utf-8\?Q\?B\=C3\=B6ckel\=22's\?\= message of "Sun,
	2 Sep 2018 01:16:39 +0200")
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To: Lars =?utf-8?Q?B=C3=B6ckel?= <listdump@larf.space>
Cc: guix-devel@gnu.org

Hi Lars,

Lars B=C3=B6ckel <listdump@larf.space> skribis:

> 2) Using a modified QEMU with libvirt. A modified QEMU could help
> sometimes. A way to specify which QEMU package to use would be helpful
> to resolve issues with newer qemu versions or patches which are not
> upstream. While in NixOS you could add patches like this
>
> =C2=A0=C2=A0=C2=A0 nixpkgs.config.packageOverrides =3D pkgs: rec {
> =C2=A0=C2=A0=C2=A0 qemu =3D pkgs.qemu.overrideAttrs (attrs:{
> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 patches =3D (lib.filter (x: ! (lib.hasSuff=
ix
> "fix-hda-recording.patch" (builtins.toString x)))=C2=A0 attrs.patches) ++=
 [
> /path/to/qemu.patch=C2=A0=C2=A0=C2=A0 ];
> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 }
> =C2=A0=C2=A0 =C2=A0);
> =C2=A0 };
>
> to the QEMU package, i don't think this is possible in GuixSD.

As G=C3=A1bor suggested, you would do it along these lines:

  (define qemu-patched
    (package
      (inherit qemu)
      =E2=80=A6))

  (define custom-libvirt
    (package
      (inherit libvirt)
      (inputs `(("qemu" ,qemu-patched)
                ,@(alist-delete "qemu" (package-inputs libvirt))))))

  (operating-system
    ;; =E2=80=A6
    (services (cons (service libvirt-service-type
                             (libvirt-configuration
                               (libvirt custom-libvirt)))
                    %base-services)))


It=E2=80=99s not equivalent to the above Nix snippet because it only affect=
s the
libvirt service, but it addresses this particular need.

HTH,
Ludo=E2=80=99.