[systemd-devel] [PATCH 1/2] detect-virt: detect in best-heuristic order

[Andrew Jones]

afaict, this will fix a regression caused by commit 75f86906c5.
Where we used to report "kvm" before that patch, without this patch,
we would only report "qemu". The reason is because cpuid detection
must come before dmi detection. Also, both can safely come before
other xen heuristics.
---
 src/basic/virt.c | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/src/basic/virt.c b/src/basic/virt.c
index fb181e5b55ee5..1e10fc755f201 100644
--- a/src/basic/virt.c
+++ b/src/basic/virt.c
@@ -267,12 +267,7 @@ int detect_vm(void) {
         if (cached_found >= 0)
                 return cached_found;
 
-        /* Try xen capabilities file first, if not found try
-         * high-level hypervisor sysfs file:
-         *
-         * https://bugs.freedesktop.org/show_bug.cgi?id=77271 */
-
-        r = detect_vm_xen();
+        r = detect_vm_cpuid();
         if (r < 0)
                 return r;
         if (r != VIRTUALIZATION_NONE)
@@ -284,7 +279,14 @@ int detect_vm(void) {
         if (r != VIRTUALIZATION_NONE)
                 goto finish;
 
-        r = detect_vm_cpuid();
+        /* x86 xen will most likely be detected by cpuid. If not (most likely
+         * because we're not an x86 guest), then we should try the xen capabilities
+         * file next. If that's not found, then we check for the high-level
+         * hypervisor sysfs file:
+         *
+         * https://bugs.freedesktop.org/show_bug.cgi?id=77271 */
+
+        r = detect_vm_xen();
         if (r < 0)
                 return r;
         if (r != VIRTUALIZATION_NONE)
-- 
2.4.3