+ /* Try high-level hypervisor sysfs file first:
+ *
+ * https://bugs.freedesktop.org/show_bug.cgi?id=61491 */
+ 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;
+
+ /* 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;
+ }
+
+ /* Detect User-Mode Linux by reading /proc/cpuinfo */
+ r = read_full_file("/proc/cpuinfo", &cpuinfo_contents, NULL);
+ if (r < 0)
+ return r;
+ if (strstr(cpuinfo_contents, "\nvendor_id\t: User Mode Linux\n")) {
+ _id = "uml";
+ r = 1;
+ goto finish;
+ }
+
+ r = 0;
+
+finish:
+ cached_found = r;
+
+ cached_id = _id;
+ if (id)
+ *id = _id;
+
+ return r;