[PATCH 1/4] wineboot: Initialize user shared data Qpc flags and frequency.

[Rémi Bernon]

Signed-off-by: Rémi Bernon <rbernon at codeweavers.com>
---

This is probably more an RFC but I don't expect it to be merged right
away anyway. It fixes the high overhead (Rtl)QueryPerformanceCounter now
have with the new syscall frames. There's a few things I'm still not
completely confident with:

* The reported Qpc frequency now changes from the default 10MHz. This is
  also the case on some Windows version (since they introduced QpcBypass
  but before they introduced the hypervisor page), and applications
  shouldn't rely on a fixed frequency, but we can expect that some do.

  Since the hypervisor page, the reported frequency is 10MHz again, and
  the divider is stored in the new shared page. We could very well
  implement the same thing, but it required the new shared memory page
  to be introduced.

* The rdtsc(p) frequency calibration done when we cannot get the
  information from cpuid (on AMD and older Intel CPU) is still a little
  bit imprecise, and I'm not sure how to make it better while keeping
  the calibration time small. On my computer I can see a ±100KHz error
  for a nominal 3.6GHz frequency. I believe the Linux kernel also does
  some estimation there, but it has access to hardware timers that may
  help to get a better approximation.

 programs/wineboot/wineboot.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/programs/wineboot/wineboot.c b/programs/wineboot/wineboot.c
index 9427448b612..9e36b3c22dd 100644
--- a/programs/wineboot/wineboot.c
+++ b/programs/wineboot/wineboot.c
@@ -82,6 +82,8 @@
 
 WINE_DEFAULT_DEBUG_CHANNEL(wineboot);
 
+#define TICKSPERSEC        10000000
+
 extern BOOL shutdown_close_windows( BOOL force );
 extern BOOL shutdown_all_desktops( BOOL force );
 extern void kill_processes( BOOL kill_desktop );
@@ -241,12 +243,28 @@ static void initialize_xstate_features(struct _KUSER_SHARED_DATA *data)
     TRACE("XSAVE feature 2 %#x, %#x, %#x, %#x.\n", regs[0], regs[1], regs[2], regs[3]);
 }
 
+static void initialize_qpc_features(struct _KUSER_SHARED_DATA *data)
+{
+    data->QpcBypassEnabled = 0;
+    data->QpcFrequency = TICKSPERSEC;
+    data->QpcShift = 0;
+    data->QpcBias = 0;
+}
+
 #else
 
 static void initialize_xstate_features(struct _KUSER_SHARED_DATA *data)
 {
 }
 
+static void initialize_qpc_features(struct _KUSER_SHARED_DATA *data)
+{
+    data->QpcBypassEnabled = 0;
+    data->QpcFrequency = TICKSPERSEC;
+    data->QpcShift = 0;
+    data->QpcBias = 0;
+}
+
 #endif
 
 static void create_user_shared_data(void)
@@ -336,6 +354,7 @@ static void create_user_shared_data(void)
     data->ActiveGroupCount = 1;
 
     initialize_xstate_features( data );
+    initialize_qpc_features( data );
 
     UnmapViewOfFile( data );
 }
-- 
2.30.2