Check requiredSystemFeatures for local builds

For example, this prevents a "kvm" build on machines that don't have
KVM.

Fixes #2012.

1 files changed, 6 insertions, 0 deletions

diff --git a/src/libstore/globals.hh b/src/libstore/globals.hh
index f589078dbb98..cf4ae63cdc2f 100644
--- a/src/libstore/globals.hh
+++ b/src/libstore/globals.hh
@@ -32,6 +32,8 @@ class Settings : public Config {
 
     unsigned int getDefaultCores();
 
+    StringSet getDefaultSystemFeatures();
+
 public:
 
     Settings();
@@ -261,6 +263,10 @@ public:
         "These may be supported natively (e.g. armv7 on some aarch64 CPUs "
         "or using hacks like qemu-user."};
 
+    Setting<StringSet> systemFeatures{this, getDefaultSystemFeatures(),
+        "system-features",
+        "Optional features that this system implements (like \"kvm\")."};
+
     Setting<Strings> substituters{this,
         nixStore == "/nix/store" ? Strings{"https://cache.nixos.org/"} : Strings(),
         "substituters",