Improve README.

1 files changed, 22 insertions, 4 deletions

diff --git a/README.md b/README.md
index 8634a17..2b7c5ad 100644
--- a/README.md
+++ b/README.md
@@ -4,8 +4,26 @@ doesn't want root privileges.
 
 To build it, you need GNAT 4.x or higher (Ada 2005 support required).
 Just use "make" in the top level dir.
+Alternatively, you can use gnatmake directly, from the top level dir do
 
-Currently CPUID-based checks that can detect KVM, Xen, VMWare, and Hyper-V
-are supported on any OS, but SMBIOS vendor checks are Linux-specific.
-If you know how to extend them to other OSes, patches are welcome
-(as long as it doesn't require root privileges, as it kinda was the motivation).
+```
+gnatmake ./src/hvinfo
+```
+
+# OS and hypervisor support
+
+CPUID-based checks that can detext KVM, Xen HVM, VMware, and Hyper-V are
+supported on any OS.
+
+Xen PV vs. Xen HVM check is supported on Linux and FreeBSD.
+
+The easiest way to detect VirtualBox, Parallels, and some other hypervisors
+that don't use CPUID identification is to check SMBIOS vendor name,
+and this is currently only supported on Linux because it provides DMI information
+via sysfs.
+
+Container systems such as LXC and OpenVZ are not supported yet.
+
+Virtualization systems for platforms other than x86 aren't supported either.
+
+Patches are welcome.