virt: add comment about order in virtualization detection

diff --git a/src/basic/virt.c b/src/basic/virt.c
index a3811054284e242e4d06d675f9c5258e39b0ea02..bccde00f77a50eaff80f348774c3307a151f16bc 100644 (file)
--- a/src/basic/virt.c
+++ b/src/basic/virt.c
@@ -270,6 +270,13 @@ int detect_vm(void) {
         if (cached_found >= 0)
                 return cached_found;
 
+        /* We have to use the correct order here:
+         * Some virtualization technologies do use KVM hypervisor but are
+         * expected to be detected as something else. So detect DMI first.
+         *
+         * An example is Virtualbox since version 5.0, which uses KVM backend.
+         * Detection via DMI works corretly, the CPU ID would find KVM
+         * only. */
         r = detect_vm_dmi();
         if (r < 0)
                 return r;