From bff939b373c18c3b871391be4edd8598eb01cb6e Mon Sep 17 00:00:00 2001 From: Chris Bednarski Date: Thu, 19 May 2016 22:53:53 -0700 Subject: [PATCH] Added comment on why we need to open /dev/kvm before using it --- builder/qemu/builder.go | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/builder/qemu/builder.go b/builder/qemu/builder.go index e1c2dc059..2c7418180 100644 --- a/builder/qemu/builder.go +++ b/builder/qemu/builder.go @@ -154,6 +154,10 @@ func (b *Builder) Prepare(raws ...interface{}) ([]string, error) { if runtime.GOOS == "windows" { b.config.Accelerator = "tcg" } else { + // /dev/kvm is a kernel module that may be loaded if kvm is + // installed and the host supports VT-x extensions. To make sure + // this will actually work we need to os.Open() it. If os.Open fails + // the kernel module was not installed or loaded correctly. if fp, err := os.Open("/dev/kvm"); err != nil { b.config.Accelerator = "tcg" } else {