Libguestfs - Oct 2015 - [PATCH 1/2] launch: direct: Use a single -machine [type, ]accel=... option.

Previously we used (on arm): -M virt -machine accel=...

After this change, we use: -machine virt,accel=...
On x86 there is no change.

The -M option is an abbreviation for -machine, and we can combine the
two options together.  (Qemu combines the two options internally, but
it's more predictable if we do it ourselves).

Upstream qemu has supported the -machine option for over 5 years, and
in fact we implicitly relied on it (despite what the comment in the
code said).
---
 src/launch-direct.c | 52 +++++++++++++++++++---------------------------------
 1 file changed, 19 insertions(+), 33 deletions(-)

diff --git a/src/launch-direct.c b/src/launch-direct.c
index 44ae9d0..2ffbff1 100644
--- a/src/launch-direct.c
+++ b/src/launch-direct.c
@@ -376,11 +376,6 @@ launch_direct (guestfs_h *g, void *datav, const char *arg)
   ADD_CMDLINE ("-display");
   ADD_CMDLINE ("none");
 
-#ifdef MACHINE_TYPE
-  ADD_CMDLINE ("-M");
-  ADD_CMDLINE (MACHINE_TYPE);
-#endif
-
   /* See guestfs.pod / gdb */
   if (guestfs_int_get_backend_setting_bool (g, "gdb") > 0) {
     ADD_CMDLINE ("-S");
@@ -388,35 +383,26 @@ launch_direct (guestfs_h *g, void *datav, const char *arg)
     warning (g, "qemu debugging is enabled, connect gdb to tcp::1234 to
begin");
   }
 
+  ADD_CMDLINE ("-machine");
+  if (!force_tcg)
+    ADD_CMDLINE (
+#ifdef MACHINE_TYPE
+                 MACHINE_TYPE ","
+#endif
+                 "accel=kvm:tcg");
+  else
+    ADD_CMDLINE (
+#ifdef MACHINE_TYPE
+                 MACHINE_TYPE ","
+#endif
+                 "accel=tcg");
+
   cpu_model = guestfs_int_get_cpu_model (has_kvm && !force_tcg);
   if (cpu_model) {
     ADD_CMDLINE ("-cpu");
     ADD_CMDLINE (cpu_model);
   }
 
-  /* The qemu -machine option (added 2010-12) is a bit more sane
-   * since it falls back through various different acceleration
-   * modes, so try that first (thanks Markus Armbruster).
-   */
-  if (qemu_supports (g, data, "-machine")) {
-    ADD_CMDLINE ("-machine");
-    if (!force_tcg)
-      ADD_CMDLINE ("accel=kvm:tcg");
-    else
-      ADD_CMDLINE ("accel=tcg");
-  } else {
-    /* qemu sometimes needs this option to enable hardware
-     * virtualization, but some versions of 'qemu-kvm' will use KVM
-     * regardless (even where this option appears in the help text).
-     * It is rumoured that there are versions of qemu where
-     * supplying this option when hardware virtualization is not
-     * available will cause qemu to fail.  A giant clusterfuck with
-     * the qemu command line, again.
-     */
-    if (has_kvm && !force_tcg && qemu_supports (g, data,
"-enable-kvm"))
-      ADD_CMDLINE ("-enable-kvm");
-  }
-
   if (g->smp > 1) {
     ADD_CMDLINE ("-smp");
     ADD_CMDLINE_PRINTF ("%d", g->smp);
@@ -997,12 +983,12 @@ test_qemu (guestfs_h *g, struct backend_direct_data *data)
   guestfs_int_cmd_add_arg (cmd3, g->hv);
   guestfs_int_cmd_add_arg (cmd3, "-display");
   guestfs_int_cmd_add_arg (cmd3, "none");
-#ifdef MACHINE_TYPE
-  guestfs_int_cmd_add_arg (cmd3, "-M");
-  guestfs_int_cmd_add_arg (cmd3, MACHINE_TYPE);
-#endif
   guestfs_int_cmd_add_arg (cmd3, "-machine");
-  guestfs_int_cmd_add_arg (cmd3, "accel=kvm:tcg");
+  guestfs_int_cmd_add_arg (cmd3,
+#ifdef MACHINE_TYPE
+                           MACHINE_TYPE ","
+#endif
+                           "accel=kvm:tcg");
   guestfs_int_cmd_add_arg (cmd3, "-device");
   guestfs_int_cmd_add_arg (cmd3, "?");
   guestfs_int_cmd_clear_capture_errors (cmd3);
-- 
2.5.2

Making -machine configurable would be a really bad idea.
---
 src/guestfs-internal.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/guestfs-internal.h b/src/guestfs-internal.h
index 7f1e572..113705d 100644
--- a/src/guestfs-internal.h
+++ b/src/guestfs-internal.h
@@ -133,7 +133,7 @@
 #define VIRTIO_NET "virtio-net-device"
 #endif /* ARM */
 
-/* Machine types.  XXX Make these configurable. */
+/* Machine types. */
 #ifdef __arm__
 #define MACHINE_TYPE "virt"
 #endif
-- 
2.5.2