--- /dev/null
+Index: include/iprt/time.h
+===================================================================
+--- include/iprt/time.h (revision 83470)
++++ include/iprt/time.h (revision 83471)
+@@ -359,6 +359,12 @@
+ /* PORTME: Add struct timeval guard macro here. */
+ #if defined(RTTIME_INCL_TIMEVAL) || defined(_STRUCT_TIMEVAL) || defined(_SYS__TIMEVAL_H_) || defined(_SYS_TIME_H) || defined(_TIMEVAL) || defined(_LINUX_TIME_H) \
+ || (defined(RT_OS_NETBSD) && defined(_SYS_TIME_H_))
++/*
++ * Starting with Linux kernel version 5.6-rc3, the struct timeval is no longer
++ * available to kernel code and must not be used in kernel code.
++ * Only 64-bit time-interfaces are allowed into the kernel.
++ */
++# if defined(RT_OS_LINUX) && (!defined(__KERNEL__) || !defined(_LINUX_TIME64_H))
+ /**
+ * Gets the time as POSIX timeval.
+ *
+@@ -392,6 +398,7 @@
+ {
+ return RTTimeSpecAddMicro(RTTimeSpecSetSeconds(pTime, pTimeval->tv_sec), pTimeval->tv_usec);
+ }
++# endif /* RT_OS_LINUX ... */
+ #endif /* various ways of detecting struct timeval */
+
+
+@@ -431,15 +438,19 @@
+ {
+ return RTTimeSpecAddNano(RTTimeSpecSetSeconds(pTime, pTimespec->tv_sec), pTimespec->tv_nsec);
+ }
++#endif /* various ways of detecting struct timespec */
+
+-
+-# ifdef _LINUX_TIME64_H
++#if defined(RT_OS_LINUX) && defined(_LINUX_TIME64_H)
++/*
++ * Starting with Linux kernel version 5.6-rc3, the _STRUCT_TIMESPEC is only defined
++ * under !__KERNEL__ guard and _LINUX_TIME64_H does not define a corresponding
++ * _STRUCT_TIMESPEC64. Only 64-bit time-interfaces are now allowed into the kernel.
++ */
+ DECLINLINE(PRTTIMESPEC) RTTimeSpecSetTimespec64(PRTTIMESPEC pTime, const struct timespec64 *pTimeval)
+ {
+ return RTTimeSpecAddNano(RTTimeSpecSetSeconds(pTime, pTimeval->tv_sec), pTimeval->tv_nsec);
+ }
+-# endif
+-#endif /* various ways of detecting struct timespec */
++#endif /* RT_OS_LINUX && _LINUX_TIME64_H */
+
+
+
+Index: src/VBox/Runtime/r0drv/linux/memobj-r0drv-linux.c
+===================================================================
+--- src/VBox/Runtime/r0drv/linux/memobj-r0drv-linux.c (revision 83470)
++++ src/VBox/Runtime/r0drv/linux/memobj-r0drv-linux.c (revision 83471)
+@@ -1461,9 +1461,19 @@
+ * MMIO / physical memory.
+ */
+ Assert(pMemLnxToMap->Core.enmType == RTR0MEMOBJTYPE_PHYS && !pMemLnxToMap->Core.u.Phys.fAllocated);
++#if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 25)
++ /*
++ * ioremap() defaults to no caching since the 2.6 kernels.
++ * ioremap_nocache() has been removed finally in 5.6-rc1.
++ */
+ pMemLnx->Core.pv = pMemLnxToMap->Core.u.Phys.uCachePolicy == RTMEM_CACHE_POLICY_MMIO
++ ? ioremap(pMemLnxToMap->Core.u.Phys.PhysBase + offSub, cbSub)
++ : ioremap_cache(pMemLnxToMap->Core.u.Phys.PhysBase + offSub, cbSub);
++#else /* KERNEL_VERSION < 2.6.25 */
++ pMemLnx->Core.pv = pMemLnxToMap->Core.u.Phys.uCachePolicy == RTMEM_CACHE_POLICY_MMIO
+ ? ioremap_nocache(pMemLnxToMap->Core.u.Phys.PhysBase + offSub, cbSub)
+ : ioremap(pMemLnxToMap->Core.u.Phys.PhysBase + offSub, cbSub);
++#endif /* KERNEL_VERSION < 2.6.25 */
+ if (pMemLnx->Core.pv)
+ {
+ /** @todo fix protection. */
+Index: src/VBox/Runtime/r0drv/linux/time-r0drv-linux.c
+===================================================================
+--- src/VBox/Runtime/r0drv/linux/time-r0drv-linux.c (revision 83470)
++++ src/VBox/Runtime/r0drv/linux/time-r0drv-linux.c (revision 83471)
+@@ -38,12 +38,24 @@
+
+ DECLINLINE(uint64_t) rtTimeGetSystemNanoTS(void)
+ {
+-#if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 16) /* This must match timer-r0drv-linux.c! */
++#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 6, 0)
+ /*
++ * Starting with kernel version 5.6-rc3 only 64-bit time interfaces
++ * are allowed in the kernel.
++ */
++ uint64_t u64;
++ struct timespec64 Ts = { 0, 0 };
++
++ ktime_get_ts64(&Ts);
++ u64 = Ts.tv_sec * RT_NS_1SEC_64 + Ts.tv_nsec;
++ return u64;
++
++#elif LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 16) /* This must match timer-r0drv-linux.c! */
++ /*
+ * Use ktime_get_ts, this is also what clock_gettime(CLOCK_MONOTONIC,) is using.
+ */
+ uint64_t u64;
+- struct timespec Ts;
++ struct timespec Ts = { 0, 0 };
+ ktime_get_ts(&Ts);
+ u64 = Ts.tv_sec * RT_NS_1SEC_64 + Ts.tv_nsec;
+ return u64;
+Index: src/VBox/HostDrivers/VBoxPci/linux/VBoxPci-linux.c
+===================================================================
+--- src/VBox/HostDrivers/VBoxPci/linux/VBoxPci-linux.c (revision 83470)
++++ src/VBox/HostDrivers/VBoxPci/linux/VBoxPci-linux.c (revision 83471)
+@@ -842,15 +842,27 @@
+ rcLnx = pci_request_region(pPciDev, iRegion, "vboxpci");
+ if (!rcLnx)
+ {
++#if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 25)
++ /*
++ * ioremap() defaults to no caching since the 2.6 kernels.
++ * ioremap_nocache() has been removed finally in 5.6-rc1.
++ */
++ RTR0PTR R0PtrMapping = ioremap(pci_resource_start(pPciDev, iRegion),
++ pci_resource_len(pPciDev, iRegion));
++#else /* KERNEL_VERSION < 2.6.25 */
+ /* For now no caching, try to optimize later. */
+ RTR0PTR R0PtrMapping = ioremap_nocache(pci_resource_start(pPciDev, iRegion),
+ pci_resource_len(pPciDev, iRegion));
+-
++#endif /* KERNEL_VERSION < 2.6.25 */
+ if (R0PtrMapping != NIL_RTR0PTR)
+ pIns->aRegionR0Mapping[iRegion] = R0PtrMapping;
+ else
+ {
++#if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 25)
++ vbpci_printk(KERN_DEBUG, pPciDev, "ioremap() failed\n");
++#else
+ vbpci_printk(KERN_DEBUG, pPciDev, "ioremap_nocache() failed\n");
++#endif
+ pci_release_region(pPciDev, iRegion);
+ rc = VERR_MAP_FAILED;
+ }
+Index: include/iprt/time.h
+===================================================================
+--- include/iprt/time.h (revision 83472)
++++ include/iprt/time.h (revision 83473)
+@@ -357,14 +357,18 @@
+
+
+ /* PORTME: Add struct timeval guard macro here. */
+-#if defined(RTTIME_INCL_TIMEVAL) || defined(_STRUCT_TIMEVAL) || defined(_SYS__TIMEVAL_H_) || defined(_SYS_TIME_H) || defined(_TIMEVAL) || defined(_LINUX_TIME_H) \
+- || (defined(RT_OS_NETBSD) && defined(_SYS_TIME_H_))
+ /*
+ * Starting with Linux kernel version 5.6-rc3, the struct timeval is no longer
+ * available to kernel code and must not be used in kernel code.
+ * Only 64-bit time-interfaces are allowed into the kernel.
+ */
+-# if defined(RT_OS_LINUX) && (!defined(__KERNEL__) || !defined(_LINUX_TIME64_H))
++#if defined(RT_OS_LINUX) && (defined(__KERNEL__) || defined(_LINUX_TIME64_H))
++#define RTTIME_NO_TIMEVAL
++#endif
++#if !defined(RTTIME_NO_TIMEVAL) \
++ && (defined(RTTIME_INCL_TIMEVAL) || defined(_STRUCT_TIMEVAL) || defined(_SYS__TIMEVAL_H_) \
++ || defined(_SYS_TIME_H) || defined(_TIMEVAL) || defined(_LINUX_TIME_H) \
++ || (defined(RT_OS_NETBSD) && defined(_SYS_TIME_H_)))
+ /**
+ * Gets the time as POSIX timeval.
+ *
+@@ -398,7 +402,6 @@
+ {
+ return RTTimeSpecAddMicro(RTTimeSpecSetSeconds(pTime, pTimeval->tv_sec), pTimeval->tv_usec);
+ }
+-# endif /* RT_OS_LINUX ... */
+ #endif /* various ways of detecting struct timeval */
+
+
+Index: include/iprt/time.h
+===================================================================
+--- include/iprt/time.h (revision 83483)
++++ include/iprt/time.h (revision 83484)
+@@ -406,8 +406,20 @@
+
+
+ /* PORTME: Add struct timespec guard macro here. */
+-#if defined(RTTIME_INCL_TIMESPEC) || defined(_STRUCT_TIMESPEC) || defined(_SYS__TIMESPEC_H_) || defined(TIMEVAL_TO_TIMESPEC) || defined(_TIMESPEC) \
+- || (defined(RT_OS_NETBSD) && defined(_SYS_TIME_H_))
++/*
++ * Starting with Linux kernel version 5.6-rc3, the _STRUCT_TIMESPEC is only defined
++ * under !__KERNEL__ guard and _LINUX_TIME64_H does not define a corresponding
++ * _STRUCT_TIMESPEC64. Only 64-bit time-interfaces are now allowed into the kernel.
++ * We have to keep it for __KERNEL__ though to support older guest kernels (2.6.X)
++ * without _LINUX_TIME64_H.
++ */
++#if defined(RT_OS_LINUX) && defined(_LINUX_TIME64_H)
++#define RTTIME_NO_TIMESPEC
++#endif
++#if !defined(RTTIME_NO_TIMESPEC) \
++ && (defined(RTTIME_INCL_TIMESPEC) || defined(_STRUCT_TIMESPEC) || defined(_SYS__TIMESPEC_H_) \
++ || defined(TIMEVAL_TO_TIMESPEC) || defined(_TIMESPEC) \
++ || (defined(RT_OS_NETBSD) && defined(_SYS_TIME_H_)))
+ /**
+ * Gets the time as POSIX timespec.
+ *
+@@ -443,12 +455,7 @@
+ }
+ #endif /* various ways of detecting struct timespec */
+
+-#if defined(RT_OS_LINUX) && defined(_LINUX_TIME64_H)
+-/*
+- * Starting with Linux kernel version 5.6-rc3, the _STRUCT_TIMESPEC is only defined
+- * under !__KERNEL__ guard and _LINUX_TIME64_H does not define a corresponding
+- * _STRUCT_TIMESPEC64. Only 64-bit time-interfaces are now allowed into the kernel.
+- */
++#if defined(RTTIME_NO_TIMESPEC)
+ DECLINLINE(PRTTIMESPEC) RTTimeSpecSetTimespec64(PRTTIMESPEC pTime, const struct timespec64 *pTimeval)
+ {
+ return RTTimeSpecAddNano(RTTimeSpecSetSeconds(pTime, pTimeval->tv_sec), pTimeval->tv_nsec);
+Index: src/VBox/Runtime/r0drv/linux/time-r0drv-linux.c
+===================================================================
+--- src/VBox/Runtime/r0drv/linux/time-r0drv-linux.c (revision 83483)
++++ src/VBox/Runtime/r0drv/linux/time-r0drv-linux.c (revision 83484)
+@@ -194,9 +194,9 @@
+ IPRT_LINUX_RESTORE_EFL_AC();
+ # ifdef _LINUX_TIME64_H
+ return RTTimeSpecSetTimespec64(pTime, &Ts);
+-#else
++# else
+ return RTTimeSpecSetTimespec(pTime, &Ts);
+-#endif
++# endif
+ #else /* < 2.6.16 */
+ struct timeval Tv;
+ do_gettimeofday(&Tv);