+ /* Try xen capabilities file first, if not found try high-level hypervisor sysfs file:
+ *
+ * https://bugs.freedesktop.org/show_bug.cgi?id=77271 */
+ r = read_one_line_file("/proc/xen/capabilities", &domcap);
+ if (r >= 0) {
+ char *cap, *i = domcap;
+
+ while ((cap = strsep(&i, ",")))
+ if (streq(cap, "control_d"))
+ break;
+
+ if (!cap) {
+ _id = "xen";
+ r = 1;
+ }
+
+ goto finish;
+
+ } else if (r == -ENOENT) {
+ _cleanup_free_ char *hvtype = NULL;
+
+ r = read_one_line_file("/sys/hypervisor/type", &hvtype);
+ if (r >= 0) {
+ if (streq(hvtype, "xen")) {
+ _id = "xen";
+ r = 1;
+ goto finish;
+ }
+ } else if (r != -ENOENT)
+ return r;
+ } else
+ return r;
+
+ /* this will set _id to "other" and return 0 for unknown hypervisors */
+ r = detect_vm_cpuid(&_id);
+ if (r != 0)
+ goto finish;
+
+ r = detect_vm_dmi(&_id);
+ if (r != 0)
+ goto finish;
+
+ if (_id) {
+ /* "other" */
+ r = 1;
+ goto finish;
+ }