Re: [XENIFACE PATCH] xenagent: Add DisableTimeSync option

["Tu Dinh" <ngoc-tu.dinh@xxxxxxxxxx>]

Hi Owen,

On 09/07/2025 09:49, Owen Smith wrote:
> Reviewed-by: Owen Smith <owen.smith@xxxxxxxxx <mailto:owen.smith@xxxxxxxxx>>
>
> XenServer has had patches that does something similar for a while, and
> contains other related options - I've been meaning to clean it up and
> upstream for a while, but its embedded in a pretty hefty refactoring of
> the xenagent code.
>

I was not aware of TimeSyncMode. Let's converge on the existing
TimeSyncMode setting. I can make it respect TimeSyncMode=0.

>
> On Tue, Jul 8, 2025 at 3:48 PM Tu Dinh <ngoc-tu.dinh@xxxxxxxxxx> wrote:
>
>     xenagent's time sync mechanism interferes with w32time's own time sync,
>     especially in a domain environment where domain members are expected to
>     follow the PDCe.
>
>     Add a REG_DWORD value DisableTimeSync in xenagent\Parameters to allow
>     disabling the XenTime sync.
>     Note that this setting is not honored during time sync attempts after
>     resume.
>
>     Also add an empty xenagent\Parameters key in xeniface.inf to ease
>     creating the setting.
>
>     Signed-off-by: Tu Dinh <ngoc-tu.dinh@xxxxxxxxxx>
>     ---
>       src/xenagent/service.cpp        |  4 ++--
>       src/xenagent/xenifacedevice.cpp | 32 ++++++++++++++++++++++++++++----
>       src/xenagent/xenifacedevice.h   |  4 ++--
>       src/xeniface.inf                |  4 ++++
>       4 files changed, 36 insertions(+), 8 deletions(-)
>
>     diff --git a/src/xenagent/service.cpp b/src/xenagent/service.cpp
>     index 535d761..6ef7b1a 100644
>     --- a/src/xenagent/service.cpp
>     +++ b/src/xenagent/service.cpp
>     @@ -216,7 +216,7 @@ bool CXenAgent::ServiceMainLoop()
>
>           case WAIT_OBJECT_0+2:
>               ResetEvent(m_xeniface.m_evt_suspend);
>     -        m_xeniface.CheckXenTime();
>     +        m_xeniface.CheckXenTime(true);
>               m_xeniface.CheckSuspend();
>               return true; // continue loop
>
>     @@ -230,7 +230,7 @@ bool CXenAgent::ServiceMainLoop()
>               return true; // continue loop
>           }
>           case WAIT_TIMEOUT:
>     -        m_xeniface.CheckXenTime();
>     +        m_xeniface.CheckXenTime(false);
>               __fallthrough;
>           case WAIT_IO_COMPLETION:
>               m_xeniface.CheckSuspend();
>     diff --git a/src/xenagent/xenifacedevice.cpp b/src/xenagent/
>     xenifacedevice.cpp
>     index 69a584b..c476ccd 100644
>     --- a/src/xenagent/xenifacedevice.cpp
>     +++ b/src/xenagent/xenifacedevice.cpp
>     @@ -40,6 +40,14 @@
>       #include "xeniface_ioctls.h"
>       #include "messages.h"
>
>     +#define SERVICES_KEY "SYSTEM\\CurrentControlSet\\Services"
>     +
>     +#define SERVICE_KEY(_Service) \
>     +        SERVICES_KEY ## "\\" ## _Service
>     +
>     +#define PARAMETERS_KEY(_Service) \
>     +        SERVICE_KEY(_Service) ## "\\Parameters"
>     +
>       CXenIfaceDevice::CXenIfaceDevice(const wchar_t* path) : CDevice(path)
>       {}
>
>     @@ -213,7 +221,7 @@
>     CXenIfaceDeviceList::CXenIfaceDeviceList(CXenAgent* agent) :
>     CDeviceList(GUID_IN
>           if (m_agent->ConvDevicePresent())
>               StartSlateModeWatch(device);
>
>     -    SetXenTime(device);
>     +    SetXenTime(device, false);
>       }
>
>       /*virtual*/ void CXenIfaceDeviceList::OnDeviceRemoved(CDevice* dev)
>     @@ -339,7 +347,7 @@ bool CXenIfaceDeviceList::CheckShutdown()
>           return false;
>       }
>
>     -void CXenIfaceDeviceList::CheckXenTime()
>     +void CXenIfaceDeviceList::CheckXenTime(bool forced)
>       {
>           CCritSec crit(&m_crit);
>           CXenIfaceDevice* device = (CXenIfaceDevice*)GetFirstDevice();
>     @@ -347,7 +355,7 @@ void CXenIfaceDeviceList::CheckXenTime()
>           if (device == NULL)
>               return;
>
>     -    SetXenTime(device);
>     +    SetXenTime(device, forced);
>       }
>
>       void CXenIfaceDeviceList::CheckSuspend()
>     @@ -485,10 +493,26 @@ void
>     CXenIfaceDeviceList::AcquireShutdownPrivilege()
>           CloseHandle(token);
>       }
>
>     -void CXenIfaceDeviceList::SetXenTime(CXenIfaceDevice* device)
>     +void CXenIfaceDeviceList::SetXenTime(CXenIfaceDevice* device, bool
>     forced)
>       {
>           bool local;
>
>     +    if (!forced) {
>     +        DWORD   disable = 0;
>     +        DWORD   size = sizeof(disable);
>     +        LSTATUS lstatus;
>     +
>     +        lstatus = RegGetValue(HKEY_LOCAL_MACHINE,
>     +                              TEXT(PARAMETERS_KEY(__MODULE__)),
>     +                              TEXT("DisableTimeSync"),
>     +                              RRF_RT_DWORD,
>     +                              NULL,
>     +                              &disable,
>     +                              &size);
>     +        if (lstatus == ERROR_SUCCESS && disable)
>     +            return;
>     +    }
>     +
>           FILETIME now = { 0 };
>           if (!device->SharedInfoGetTime(&now, &local))
>               return;
>     diff --git a/src/xenagent/xenifacedevice.h b/src/xenagent/
>     xenifacedevice.h
>     index d85e469..8a89036 100644
>     --- a/src/xenagent/xenifacedevice.h
>     +++ b/src/xenagent/xenifacedevice.h
>     @@ -84,7 +84,7 @@ public:
>
>           void Log(const char* message);
>           bool CheckShutdown();
>     -    void CheckXenTime();
>     +    void CheckXenTime(bool forced);
>           void CheckSuspend();
>           bool CheckSlateMode(std::string& mode);
>           void LogIfRebootPending();
>     @@ -95,7 +95,7 @@ private:
>           void StartSlateModeWatch(CXenIfaceDevice* device);
>           void StopSlateModeWatch(CXenIfaceDevice* device);
>           void AcquireShutdownPrivilege();
>     -    void SetXenTime(CXenIfaceDevice* device);
>     +    void SetXenTime(CXenIfaceDevice* device, bool forced);
>
>       private:
>           CXenAgent*  m_agent;
>     diff --git a/src/xeniface.inf b/src/xeniface.inf
>     index 07e2a91..3b54f2a 100644
>     --- a/src/xeniface.inf
>     +++ b/src/xeniface.inf
>     @@ -110,6 +110,10 @@ ServiceType=%SERVICE_WIN32_OWN_PROCESS%
>       StartType=%SERVICE_AUTO_START%
>       ErrorControl=%SERVICE_ERROR_NORMAL%
>       ServiceBinary=%11%
>     
> \xenagent_@MAJOR_VERSION@_@MINOR_VERSION@_@MICRO_VERSION@_@BUILD_NUMBER@.exe
>     +AddReg=XenAgent_Parameters
>     +
>     +[XenAgent_Parameters]
>     +HKR,"Parameters",,0x00000010
>
>       [XenAgent_EventLog]
>       AddReg=XenAgent_AddReg
>     --
>     2.50.0.windows.2
>
>
>
>     Ngoc Tu Dinh | Vates XCP-ng Developer
>
>     XCP-ng & Xen Orchestra - Vates solutions
>
>     web: https://vates.tech <https://vates.tech>
>



Ngoc Tu Dinh | Vates XCP-ng Developer

XCP-ng & Xen Orchestra - Vates solutions

web: https://vates.tech