lib/meta.nix

@@ -86,4 +86,6 @@ rec {
         then { system = elem; }
         else { parsed = elem; };
     in lib.matchAttrs pattern platform;
+
+  enableIfAvailable = p: if p.meta.available or true then [ p ] else [];
 }

lib/systems/inspect.nix

@@ -39,12 +39,8 @@ rec {
     isAndroid      = [ { abi = abis.android; } { abi = abis.androideabi; } ];
     isMusl         = with abis; map (a: { abi = a; }) [ musl musleabi musleabihf ];
 
-    isKexecable    = map (family: { kernel = kernels.linux; cpu.family = family; })
-                       [ "x86" "arm" "aarch64" "mips" ];
     isEfi          = map (family: { cpu.family = family; })
                        [ "x86" "arm" "aarch64" ];
-    isSeccomputable = map (family: { kernel = kernels.linux; cpu.family = family; })
-                        [ "x86" "arm" "aarch64" "mips" ];
   };
 
   matchAnyAttrs = patterns:

nixos/modules/system/boot/kexec.nix

@@ -1,7 +1,7 @@
 { config, pkgs, lib, ... }:
 
 {
-  config = lib.mkIf (pkgs.kexectools != null) {
+  config = lib.mkIf (pkgs.kexectools.meta.available) {
     environment.systemPackages = [ pkgs.kexectools ];
 
     systemd.services."prepare-kexec" =

pkgs/development/libraries/libseccomp/default.nix

@@ -25,6 +25,7 @@ stdenv.mkDerivation rec {
     homepage    = "https://github.com/seccomp/libseccomp";
     license     = licenses.lgpl21;
     platforms   = platforms.linux;
+    badPlatforms = platforms.riscv;
     maintainers = with maintainers; [ thoughtpolice wkennington ];
   };
 }

pkgs/os-specific/linux/kexectools/default.nix

@@ -22,5 +22,6 @@ stdenv.mkDerivation rec {
     homepage = http://horms.net/projects/kexec/kexec-tools;
     description = "Tools related to the kexec Linux feature";
     platforms = platforms.linux;
+    badPlatforms = platforms.riscv;
   };
 }

pkgs/os-specific/linux/systemd/default.nix

@@ -41,7 +41,10 @@ in stdenv.mkDerivation rec {
   buildInputs =
     [ linuxHeaders libcap kmod xz pam acl
       /* cryptsetup */ libuuid glib libgcrypt libgpgerror libidn2
-      libmicrohttpd kexectools libseccomp libffi audit lz4 bzip2 libapparmor
+      libmicrohttpd ] ++
+      stdenv.lib.meta.enableIfAvailable kexectools ++
+      stdenv.lib.meta.enableIfAvailable libseccomp ++
+    [ libffi audit lz4 bzip2 libapparmor
       iptables gnu-efi
       # This is actually native, but we already pull it from buildPackages
       pythonLxmlEnv

pkgs/stdenv/generic/check-meta.nix

@@ -165,6 +165,7 @@ let
     isFcitxEngine = bool;
     isIbusEngine = bool;
     isGutenprint = bool;
+    badPlatforms = platforms;
   };
 
   checkMetaAttr = k: v:
@@ -174,7 +175,8 @@ let
   checkMeta = meta: if shouldCheckMeta then lib.remove null (lib.mapAttrsToList checkMetaAttr meta) else [];
 
   checkPlatform = attrs:
-    lib.any (lib.meta.platformMatch hostPlatform) attrs.meta.platforms;
+    (!(attrs ? meta.platforms) || lib.any (lib.meta.platformMatch hostPlatform) attrs.meta.platforms) &&
+    (!(attrs ? meta.badPlatforms && lib.any (lib.meta.platformMatch hostPlatform) attrs.meta.badPlatforms));
 
   # Check if a derivation is valid, that is whether it passes checks for
   # e.g brokenness or license.
@@ -189,7 +191,7 @@ let
       { valid = false; reason = "blacklisted"; errormsg = "has a blacklisted license (‘${showLicense attrs.meta.license}’)"; }
     else if !allowBroken && attrs.meta.broken or false then
       { valid = false; reason = "broken"; errormsg = "is marked as broken"; }
-    else if !allowUnsupportedSystem && !allowBroken && attrs.meta.platforms or null != null && !(checkPlatform attrs) then
+    else if !allowUnsupportedSystem && !allowBroken && !(checkPlatform attrs) then
       { valid = false; reason = "broken"; errormsg = "is not supported on ‘${hostPlatform.config}’"; }
     else if !(hasAllowedInsecure attrs) then
       { valid = false; reason = "insecure"; errormsg = "is marked as insecure"; }

pkgs/tools/package-management/nix/default.nix

@@ -30,7 +30,7 @@ let
     buildInputs = [ curl openssl sqlite xz bzip2 ]
       ++ lib.optional (stdenv.isLinux || stdenv.isDarwin) libsodium
       ++ lib.optionals is20 [ brotli ] # Since 1.12
-      ++ lib.optional (hostPlatform.isSeccomputable) libseccomp
+      ++ lib.meta.enableIfAvailable libseccomp
       ++ lib.optional ((stdenv.isLinux || stdenv.isDarwin) && is20)
           (aws-sdk-cpp.override {
             apis = ["s3"];
@@ -60,7 +60,7 @@ let
           hostPlatform != buildPlatform && hostPlatform ? nix && hostPlatform.nix ? system
       ) ''--with-system=${hostPlatform.nix.system}''
          # RISC-V support in progress https://github.com/seccomp/libseccomp/pull/50
-      ++ lib.optional (!hostPlatform.isSeccomputable) "--disable-seccomp-sandboxing";
+      ++ lib.optional (!libseccomp.meta.available) "--disable-seccomp-sandboxing";
 
     makeFlags = "profiledir=$(out)/etc/profile.d";
 

pkgs/top-level/all-packages.nix

@@ -3132,9 +3132,7 @@ with pkgs;
 
   keepalived = callPackage ../tools/networking/keepalived { };
 
-  kexectools = if hostPlatform.isKexecable
-                 then callPackage ../os-specific/linux/kexectools { }
-               else null;
+  kexectools = callPackage ../os-specific/linux/kexectools { };
 
   keybase = callPackage ../tools/security/keybase { };
 
@@ -9795,9 +9793,7 @@ with pkgs;
 
   libgroove = callPackage ../development/libraries/libgroove { };
 
-  libseccomp =  if hostPlatform.isSeccomputable
-                  then callPackage ../development/libraries/libseccomp { }
-                else null;
+  libseccomp = callPackage ../development/libraries/libseccomp { };
 
   libsecret = callPackage ../development/libraries/libsecret { };