From 24cb65efc3c34e24fc653779a4d42cf4f31c6737 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ludovic=20Court=C3=A8s?= <ludo@gnu.org>
Date: Fri, 21 Mar 2014 13:54:53 +0100
Subject: [PATCH] Make /dev/kvm optional
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The daemon now creates /dev deterministically (thanks!).  However, it
expects /dev/kvm to be present.

The patch below restricts that requirement (1) to Linux-based systems,
and (2) to systems where /dev/kvm already exists.

I’m not sure about the way to handle (2).  We could special-case
/dev/kvm and create it (instead of bind-mounting it) in the chroot, so
it’s always available; however, it wouldn’t help much since most likely,
if /dev/kvm missing, then KVM support is missing.
---
 src/libstore/build.cc | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/libstore/build.cc b/src/libstore/build.cc
index 973e7a122..e846995f7 100644
--- a/src/libstore/build.cc
+++ b/src/libstore/build.cc
@@ -2020,7 +2020,10 @@ void DerivationGoal::initChild()
                 createDirs(chrootRootDir + "/dev/pts");
                 Strings ss;
                 ss.push_back("/dev/full");
-                ss.push_back("/dev/kvm");
+#ifdef __linux__
+                if (pathExists("/dev/kvm"))
+                    ss.push_back("/dev/kvm");
+#endif
                 ss.push_back("/dev/null");
                 ss.push_back("/dev/random");
                 ss.push_back("/dev/tty");