[Qemu-devel] [PATCH v4 1/2] Force driftfix=none on previous machines

["Crístian Viana" <vianac@linux.vnet.ibm.com>]

The current value for the -rtc driftfix option is 'none'. This patch
makes sure that the old machines configuration will work the same way
even after that option changes its default value.

Signed-off-by: Crístian Viana <vianac@linux.vnet.ibm.com>
---

There's a scenario when things don't work the way I expected: when I set a
previous machine with -M, the driftfix flag value on the command line is not
used, the machine's default value overwrites it. I'm not sure if that's the
expected behavior of QEMU in those cases (if I set a machine, I can't change its
properties) or if there's a bug somewhere. This is the question I asked in a
previous e-mail (http://article.gmane.org/gmane.comp.emulators.qemu/149902).

For example,

$ x86_64-softmmu/qemu-x86_64 -M pc-1.0 --rtc driftfix=slew

will use "driftfix=none", which is the default for the machine pc-1.0, not
"driftfix=slew" as I set on the command line. That only happens if I choose
a different machine than the default one (pc-1.1 as of now); otherwise it
works fine.

Changes since v3:
- Rebase the code

 hw/pc_piix.c |    4 ++++
 1 file changed, 4 insertions(+)

diff --git a/hw/pc_piix.c b/hw/pc_piix.c
index d68f77a..ed463da 100644
--- a/hw/pc_piix.c
+++ b/hw/pc_piix.c
@@ -378,6 +378,10 @@ static QEMUMachine pc_machine_v1_1 = {
             .driver   = TYPE_USB_DEVICE,\
             .property = "full-path",\
             .value    = "no",\
+        },{\
+            .driver   = "mc146818rtc",\
+            .property = "lost_tick_policy",\
+            .value    = "discard",\
         }
 
 static QEMUMachine pc_machine_v1_0 = {
-- 
1.7.9.5