X-Git-Url: http://git.annexia.org/?p=libguestfs.git;a=blobdiff_plain;f=src%2Flaunch.c;h=0b15ce98d79fac55032a7e93788f62d0011e8c34;hp=8dfeb3150095d147d577e24b4397b1425f5f9251;hb=64841fe8957f798df12a38bd81843c7011f2c278;hpb=10167cea98f93a74abe63f0a54d3a662997e7489

diff --git a/src/launch.c b/src/launch.c
index 8dfeb31..0b15ce9 100644
--- a/src/launch.c
+++ b/src/launch.c
@@ -117,7 +117,7 @@ guestfs___rollback_cmdline (guestfs_h *g, size_t pos)
 
   assert (g->cmdline_size >= pos);
 
-  for (i = g->cmdline_size - 1; i >= pos; --i)
+  for (i = pos; i < g->cmdline_size; ++i)
     free (g->cmdline[i]);
 
   g->cmdline_size = pos;
@@ -487,21 +487,30 @@ launch_appliance (guestfs_h *g)
     if (qemu_supports (g, "-nodefconfig"))
       add_cmdline (g, "-nodefconfig");
 
-    /* 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, so we we have to check at least that
-     * /dev/kvm is openable.  That's not reliable, since /dev/kvm
-     * might be openable by qemu but not by us (think: SELinux) in
-     * which case the user would not get hardware virtualization,
-     * although at least shouldn't fail.  A giant clusterfuck with the
-     * qemu command line, again.
+    /* 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, "-enable-kvm") &&
-        is_openable (g, "/dev/kvm", O_RDWR))
-      add_cmdline (g, "-enable-kvm");
+    if (qemu_supports (g, "-machine")) {
+      add_cmdline (g, "-machine");
+      add_cmdline (g, "accel=kvm: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, so we we have to check at least that
+       * /dev/kvm is openable.  That's not reliable, since /dev/kvm
+       * might be openable by qemu but not by us (think: SELinux) in
+       * which case the user would not get hardware virtualization,
+       * although at least shouldn't fail.  A giant clusterfuck with the
+       * qemu command line, again.
+       */
+      if (qemu_supports (g, "-enable-kvm") &&
+          is_openable (g, "/dev/kvm", O_RDWR))
+        add_cmdline (g, "-enable-kvm");
+    }
 
     /* Newer versions of qemu (from around 2009/12) changed the
      * behaviour of monitors so that an implicit '-monitor stdio' is