VirtualBox 6.0.6 for PC Windows

- VMM: fixed a problem which could lead to a wrong guest behavior on AMD CPUs
- GUI: don't try to synchronize the HID LEDs if the VM window is not active or if it's minimized
- GUI: prevent a crash during startup under rare conditions
- GUI: sub-menu option to disable the guest-OS type overlay in the application dock icon on Mac OS X
- GUI: position off-screen windows to be fully visible again on relaunch
- GUI: hide the VT-x/AMD-V checkbox if raw-mode is not supported
- PC speaker passthrough: new experimental feature, available on Linux host only
- Audio: several fixes for Mac OS X hosts + guests
- Audio: properly handle default audio device changes
- USB: serveral fixes for the xHCI controller (e.g. for webcam passthrough)
- BIOS: fixed int15/AH=83/AL=00 function
- iPXE: enable the HTTP download protocol on non-Linux hosts
- Shared folders: fixed a failure to load the saved state under certain circumstances
- Guest Control: added support for (cached) Active Directory authentication in case the domain controller is not reachable
- Serial ports: raised the number of serial ports per VM from 2 to 4
- Serial ports: fix for the TCP/IP backend (Windows hosts only)
- SDK: make the Python webservice API binding work again
- Seamless mode: fixed a crash under certain circumstances
- Linux hosts: fixed the /sbin/rcvboxdrv script as well as the missing shebang in two scripts
- Linux hosts: properly uninstall Python files installed by the .run installer
- Windows hosts: hardening fix required for recent Windows insider builds
- Windows hosts: fixed Python installation path
- Windows hosts: support MTU larger than 2 KB with bridged networking
- Windows hosts / guests: properly sign binaries using a sha-256 certificate
- Windows Additions: fixed guest property enumeration of logged-in users
- Windows Additions: fixed sporadical failure of the graphics driver in Windows 10 guests
- Windows Additions: under rare circumstances no mouse movement events were delivered to the guest

- GUI: properly limit the number of VCPUs to the number of physical cores on Mac OS X.
- Audio: fixed a bug which prevented loading a saved state of a saved guests with HDA emulation.
- Audio: don't crash if the backend is unable to initialize.
- Audio: fixed audio capture on Mac OS X.
- Storage: fixed a possible crash when attaching the same ISO image multiple times to the same VM.
- BIOS: properly report if two floppy drives are attached.
- USB: fixed a problem with filters which would not capture the device under certain circumstances.
- ExtPack: black-list Extension Packs older than 4.3.30 due to incompatible changes not being properly handled in the past.
- Windows hosts: fixed a regression which caused robocopy to fail.
- Linux hosts: properly create the /sbin/rcvboxdrv symbolic link.
- Mac OS X hosts: several fixes for USB on El Capitan.
- Linux Additions: fixes for Linux 4.5.

# The following items were fixed and/or added:
* GUI: fixed wrong scrolling behaviour in the VM selector window when a VM item is dragged out of the chooser-pane area.
* GUI: fixed the validation of IPv6 port-forwarding rules.
* GUI: suppress the first-run wizard if a CD/DVD medium is inserted using the selector UI.
* GUI: fixed the Ctrl+Break key sequence scan codes.
* GUI: improved handling of text selection mouse pointer.
* Host services: fixed a crash during VM shutdown under rare conditions (5.0.6 regression).
* Shared folders: fixed a sharing violation if a file is opened to check the attributes (Windows hosts only).
* Webcam: passthrough fix for certain devices (Mac OS X hosts only).
* XHCI: fixed broken emulation if software virtualization is used.
* XHCI: several fixes.
* 3D: fixed state handling under certain conditions.
* Audio: several fixes.
* BIOS: added LBA64 support for being able to boot from huge hard disks.
* EFI: fix for Windows 10 guests.
* ExtPack: before installing an Extension Pack check if there are VMs running to prevent file system locking issues.
* rdesktop-vrdp: source code tarball fixes.
* Windows hosts: fixed hang when using VBoxAuthSimple library for VRDP external authentication.
* Windows hosts: fixed a regression which prevented it to attach to a physical network adapter having TCP/IP disabled.
* Windows hosts: fixed a regression which caused multi-port adapters to be shown as a single adapter.
* Windows hosts: fixed a regression which caused created host-only adapters to not appear in the list.
* Windows hosts: fixed host-only adapter creation issues related to Windows 10 .
* Linux hosts: .desktop file compatibility issue.
* Linux hosts / guests: fixes for RHEL 7.2.
* The command for recompiling the host kernel modules was changed again, to /sbin/rcvboxdrv setup.
* Linux hosts: some fixes for PCI passthrough (still highly experimental).
* Linux/Mac OS X hosts: fixed a VM hang during startup under certain circumstances.
* Solaris hosts: added Python 2.7 bindings.
* Mac OS X hosts: fixed a possible crash when the default input or output audio device changes.
* Mac OS X hosts: fixed a panic under certain conditions.
* Linux Additions: prevent the compiler from doing dead-code elemination on vital code in guest / host communication.
* Linux Additions: when mounting a shared folder, explicitly pass the share name so that /proc/mounts contains this name instead of 'none'.
* Linux Additions: workaround for a systemd problem in conjunction with SELinux which prevented to properly enable the 'vboxadd' service during while upgrading the Additions.

- VMM: improved support for certain Intel Atom CPUs
- VMM: system register emulation fix
- GUI: fixed immediate screenshot issue
- GUI: fixed another 3D overlay window reparenting issue when the VM is switched to fullscreen mode on X11 hosts
- GUI: fixed help index
- GUI: fixed state synchronization issue in the VM manager window when VM was paused from its runtime window
- Audio: fixed suspending/resuming audio streams on VM pause/unpause
- Audio: properly reset AC97 audio streams, otherwise there is silence until a non-48 kHz stream is played
- Audio: fixed a small emulation quirk of the AD1980 codec of the HDA device to make recent linux guests work
- USB: serveral fixes for the xHCI controller
- USB: fixed a crash under certain conditions on hosts with Linux kernels older than version 3.3
- USB: better identification of certain USB devices
- NAT: support TCP in DNS proxy
- NAT Network: fixed sporadic crashes on Windows hosts
- API: when creating differencing images (e.g. as part of a snapshot or cloning a VM) use the same disk image variant as the parent image if possible, which means that e.g. a diff image for a VMDK image split into 2 GB files will also be split
- API: event queue handling fixes preventing loss of certain events at runtime (e.g. new webcam attached), particularly important on Mac OS X hosts
- Webcam: passthrough fix for certain devices (Windows hosts only)
- VBoxManage: don't crash on snapshot restorecurrent / edit if the VM has no snapshots
- VBoxManage: don't crash on controlvm addencpassword
- Mac OS X hosts: use the correct kernel on certain hosts
- Windows hosts: fixed VRDP external authentication
- Windows hosts: allow to use a shared folder path with extended-length path prefix
- Windows hosts: fix a crash in the netfilter host driver under certain conditions
- Windows host installer: documented and fixed public properties which can be used to control the installation to some extent
- Windows host installer: fixed not starting the actual installation when showing the version information or help dialogs
- X11 Additions: added basic support for X.Org Server 1.18 (3D requires additional fixes)

# Fixed and/or added:
- GUI: Mac OS X: Restore green zoom button for VM windows (it was hidden in the previous release to avoid native full-screen issues). For Yosemite and El Capitan this button should work accordingly to the Apple HIG: Full-screen by default, maximize if the user holds the Option key.
- Serial ports: fixed wrong IRQ number for the first serial port in the ACPI tables
- API: fixed a 5.0 regression in VBoxManage setproperty defaultfrontend
- VBoxManage/vbox-img: conversion to RAW images could result in a disk image containing all zeroes
- Linux hosts: several fixes for systemd integration in .deb / .rpm packages. The command for recompiling the host kernel modules was changed to /sbin/vboxconfig
- Linux hosts: make host-only interfaces report operstate UP only when they have VMs attached
- Mac OS X hosts: fix bpf capture and accounting of traffic on bridged and host-only interfaces
- Windows guests: fixed 3D rendering issues on high resolution displays
- Windows Additions: fixed problems with 3D acceleration on Windows hosts with Intel HD graphics
- Linux Additions: fix service starting on Debian systems with systemd installed but not in use

- GUI: the update check now uses the HTTP system proxy settings by default
- GUI: About dialog improvements. Copyable version text, do not close dialog on mouse-clicks and focus losing, explicit close button at the bottom of dialog and disabled close button fix on OS X.
- GUI: fixed bug when re-assigning shortcuts
- GUI: fixed default focus button in message-box dialogs
- GUI: fixed settings dialog which is opened if the network settings need to be changed at VM startup
- GUI: fixed crash during VM start if an early error message needs to be shown, for example Linux kernel modules not present
- Bridged Networking: fixed handling of guest DHCP requests without UDP checksum when bridging to a wireless interface
- Audio: latency fixes
- Guest Control: correctly set USERNAME and USERPROFILE environment variables (Windows guests only)
- Guest Control: several fixes
- API: properly restore NAT port forwarding rules when reverting to a snapshot
- Parallel ports: Several fixes allowing to enable two parallel ports for a VM
- VBoxManage: fixed wrong output of debugvm show command
- VBoxManage: fixed hang when specifying logging groups with debugvm log starting with h, for example hex
- Windows hosts: renamed VBoxStartup.log to VBoxHardening.log and provide this log file in the GUI log viewer
- Windows hosts: fixed a small memory leak in the Windows host interface driver (VBoxNetAdp) which caused a BSOD if the driver verifier is enabled
- Windows hosts: fixed a failure to start VMs on hosts where dsound.dll is not available
- Windows hosts: another fix for VERR_LDR_MISMATCH_NATIVE errors
- Windows hosts: fixed host-to-guest communication with bridged networking
- Windows hosts: fixed broken data receiving from the serial device with the named pipe backend if Kaspersky AV is installed
- Linux hosts: Linux 4.3 compile fixes
- Linux hosts: installer fix for certain systems
- Linux hosts / guests: native systemd support for the host/guest installer scripts. The scripts for re-compiling the kernel modules are now located at /sbin/rcvboxdrv (host) and /sbin/rcvboxadd
- Mac OS X hosts: GUI-related fixes for El Capitan
- Mac OS X hosts: fixed a problem with capturing USB devices under El Capitan
- Mac OS X hosts: allow colon character on shared folders
- Linux Additions: properly set the VBoxService process ID in the PID file
- Linux Additions: Guest Control fixes
- Windows Additions: fixed shutting down VBoxTray when running with older VirtualBox host versions
- Windows Additions: fixed video playback with VLC and Windows Media Player when the WDDM driver is used and 3D is not used
- Windows Additions: prevent a possible VLC crash when the WDDM driver is used and 3D is enabled by implementing YV12 surfaces

# Fixed and/or added:
- VMM: fixed an issue with Windows 10 guest kernel debugging over the network for Hyper-V paravirtualized VMs
- VMM: fixed a bug which prevented reading the saved state of the 'PATM' unit from VirtualBox 4.3.x
- GUI: changed default OS type for Windows from Windows XP to Windows 7
- GUI: added another pre-defined guest screen resolution
- GUI: fixed update check which was broken due to changing the location of the root certificates
- GUI: fixed issues with synchronization of Caps lock / Num lock / Scroll lock on Windows hosts
- GUI: don't crash during VM shutdown if 2D video acceleration and 3D support are enabled (Mac OS X hosts only)
- GUI: several seamless fixes for certain X11 window managers, also when used in multi-screen setups
- GUI: Log window size, position and cursor-position fixes
- Audio: fixed playing leftover/deprecated audio samples
- Audio: fixed playing audio after suspending the host (5.0 regression; Linux hosts using the ALSA backend)
- Audio: fixed playing short audio samples which were chopped off formerly
- Audio: fixed distortions on OS X when the sample rate of the guest stream and host device don't match
- Storage: fixed raw disk access and flat VMDK image access which would be always opened readonly
- Storage: fixed initial encryption of VDI images after they were compacted
- VGA: fix for certain graphics modes
- NAT: don't freeze while the VM is paused if the network attachment mode is changed from/to NAT with activated port forwarding
- OVF: fixed duplicate USB controller entries in exported OVA/OVF
- Shared Folders: fixed a path separator issue
- Drag and drop: fixed crashes on OS X hosts when doing host-to-guest transfers
- VBoxManage: another attempt to not deny changing the network adapter type at VM runtime
- VBoxManage: fixed broken guestcontrol <VM-Name> list command
- VBoxManage: fixed broken Guest Control stdout/stderr output
- Mac OS X hosts: fixed remaining problems with activated SMAP
- Mac OS X hosts: fixed broken 3D support
- Linux hosts: Linux 4.2 fix
- Linux hosts: don't crash on older Linux distributions if the DBus service isn't running
- Windows hosts: fixed the VERR_LDR_MISMATCH_NATIVE error message
- Windows hosts: fix for Windows 10 build 10525 and later
- Windows hosts: fixed network adapter enumeration on Windows 10
- Windows hosts: prevent intermittent host network disconnects during VM start/shutdown with bridged networking
- Windows Additions: fixed the call to the memory allocation function
- Linux Additions: be more forgiving if the compilation of the vboxvideo module fails
- X11 Additions: fixed a number of small issues with dynamic resizing and full-screen and seamless modes.

- VMM: added support for guest crash report MSRs with Hyper-V paravirtualization
- VMM: fixed an issue causing artifically high load averages on Linux hosts
- VMM: fixed a kernel panic with thread-context hooks caused by incompatible changes made to Linux 4.2 kernels
- VMM: fixed a saved state issue with VT-x/AMD-V disabled
- VMM: fixed VERR_SUPDRV_TSC_DELTA_MEASUREMENT_FAILED Guru Meditations on certain AMD CPUs
- VMM: fixed a crash while creating a guest core dumps via the VM debug facility
- VMM: This release has AVX2 passthrough disabled on every host and AVX passthrough disabled for 64-bit VMs on 32-bit hosts. This will be properly fixed in a future 5.0.x maintenance release .
- GUI: fixed rare hang and crash on VM shutdown/poweroff
- GUI: X11: fixed few crashes caused by the Qt alien widgets feature
- GUI: X11: fixed various mini-toolbar geometry quirks like positioning, z-order, transiency issues on certain window managers
- GUI: X11: fixed mini-toolbar minimize button issue under certain window managers
- GUI: VM menu actions availability should now be properly updated on full-screen/seamless/scaled mode switches
- GUI: disk encryption password validation should be performed when user confirmed the password, not after each entered symbol
- GUI: do not change the VM/group selection in the VM Manager to the newly created VM if it was created by another client (e.g. VBoxManage)
- GUI: Mac OS X: do not treat 'almost maximized' VM windows as 'maximized', watch for the strict window geometry instead
- GUI: improve the quality in scaled mode under some circumstances
- VBoxManage: do not deny changing the network adapter type at VM runtime
- VRDP: allow Windows 10 RDP clients
- Audio: fix a possible crash on VM process termination
- Storage: improved raw disk access on OS X by unmounting any accessed volume before first use and prevent any mount attempt by the host
- 3D: basic support for saving/restoring display lists
- Drag and drop: fixed guest to host transfers on OS X hosts
- Drag and drop: fixed memory leak on Windows guests
- Shared Folders: fixed a problem with accessing CIFS shares
- Shared Folders: improved path conversion between hosts and guests with different path separators
- API: skip resetting of immutable media when the VM in saved state is started
- API: fixed method for setting medium IDs which used zero (invalid) UUIDs instead random (valid) UUIDs if no UUIDs were passed
- API: for Windows host fix detection of API client crashes which have a session open
- OVF: properly export all VBox features including the setting for paravirtualization
- Mac OS X hosts: El Capitan USB fixes
- Windows hosts: fixed crash when opening Windows dialogs from the VM process on Windows 10
- Windows hosts: fixed host-only adapter creation issues on Windows 10
- Windows hosts: fixed audio on Windows 10
- Linux hosts: more fixes for activated SMAP on Linux 3.19 and newer
- Linux hosts: check then name space before attaching to a host network interface
- Linux Additions: Linux 4.2 fixes
- Linux Additions: improved the performance of stat() to speed up certain file operations on shared folders
- Windows Additions: fixed a potential crash in the WDDM driver with Windows 10
- Solaris Additions: added support for X.Org Server 1.17
- X11 Additions: various seamless mode fixes, including invisible windows under LXDE.

# New features:
- Paravirtualization support for Windows and Linux guests to improve time-keeping accuracy and performance (see the manual for more information)
- Make more instruction set extensions available to the guest when running with hardware-assisted virtualization and nested paging. Among others this includes: SSE 4.1, SSE4.2, AVX, AVX-2, AES-NI, POPCNT, RDRAND and RDSEED
- xHCI Controller to support USB 3 devices (see the manual for more information)
- Drag and drop support (bidirectional) for Windows, Linux and Solaris guests
- Disk image encryption (see the manual for more information)
- VMs can now be started in separate mode. The VM process is started headless while the frontend runs as a separate process which can be terminated without stopping the VM.
- GUI: VM guest-content scaling support (including 3D acceleration)
- GUI: New User Interface settings page for customizing status-bar, menu-bar and guest-content scaling
- GUI: New Encryption settings tab for customizing encryption options for disk images
- GUI: HiDPI support including application icons and optional unscaled HiDPI output on Mac OS X (including 3D acceleration)
- GUI: Hotplugging support for SATA disks
- New, modular audio architecture for providing a better abstraction of the host audio backends
- Support for the NDIS6 networking framework on Windows (default on Vista and later)
# Fixed and/or added:
- VMM: improved timing on Solaris hosts with older VT-x hosts without preemption timers
- VMM: further improvements for TSC frequency measurements and guest timekeeping
- VMM: debug facility now includes the guest CPU's FPU/SSE/extended state in the core dump
- VMM: fixed a hang under rare conditions on 32-bit hosts
- VMM: several fixes
- GUI: improved HID LEDs synchronization for Mac and Windows hosts. The physical LEDs state now restored together with the VM state.
- GUI: take the guest screen aspect ratio into account for the preview window
- GUI: provide direct access to storage media in the VM selector
- GUI: allow to save the VM state from the selector even if the VM is already paused
- VBoxManage: when exporting an appliance, support the suppression of MAC addresses, which means they will be always recreated on import, avoiding duplicate MAC addresses for VMs which are imported several times
- VBoxManage: now supports renaming storage controllers and USB controllers
- Guest Control: major overhaul, for example fixing wrong parameter quoting
- USB: added USB traffic capturing (see the manual for more information)
- Made resizing X11 guests work more reliably
- API: block the removal of the current snapshot if it has child snapshots (only relevant for VMs without snapshottable hard disks, their presence always prevented removal), which resulted in VM config corruption
- API: mark VM configs with snapshots but without current snapshot as inaccessible, as this combination is nonsense
- API: fix information for some automatically generated events (only with XPCOM, Windows host was not affected), which caused errors when getting some of the attributes over the webservice
- API: fix crashes in Java API clients using the XPCOM binding, happened with output parameters only
- API: a number of settings (e.g. network settings) can now also be changed when the VM is in saved state
- API: fixed incorrect resuming of VMs on host-resume unless they were previously paused due to a host-suspend
- API: don't lose the saved state and "current state changed" flag during cloning of a VM
- API: OS type description consistency fix
- VBoxSVC: don't keep the support driver permanently open
- Main/Properties: properly drop transient guest properties when the VM is powered off
- VRDP: fixed a couple of races which may cause a crash during VM poweroff
- ExtPack: don't fail if the TMP directory contains non-latin1 characters
- 3D: fix potential race in which might cause a crash on VM termination
- 3D: fixed a possible memory leak in the host service
- Serial: new TCP/IP backend (see the manual for more information)
- Storage: added USB mass storage device class (see the manual for more information)
- Storage: added vbox-img standalone tool for direct manipulation of virtual hard disk images without VBoxManage
- Storage: fixed crash as a result of I/O errors in certain conditions
- NAT: fixed several potential crashes
- NAT: don't forcibly reset/drop all connections when the link goes down
- Netsniffer: properly handle changing of the trace file name at VM runtime
- Audio: fixed audio output and input when changing the default audio device more than once on OS X
- Audio: fixed audio input on OS X under certain circumstances
- ICH9: fixed the interrupt disable logic for MSI interrupts; should fix old Linux guests with AHCI
- USB: improve playback with USB sound devices attached to the emulated OHCI controller
- Audio: provide Linux guests a different AC97 audio codec type so Linux ALSA does not mis-detect the link speed (default for new VMs)
- BIOS: fix for booting from SCSI CD/DVD media
- BIOS: fix for reads partially beyond end of disk
- VRDP: fixed listening for IPv6 on some systems
- rdesktop-vrdp: upgraded to version 1.8.3
- Linux hosts: fixed a bug which made the netfilter driver ignore certain events
- Mac OS X hosts: El Capitan fixes
- Mac OS X hosts: fixed a bug which might trigger a host kernel panic if a VM is started and another hypervisor is active
- Solaris hosts: installer fix for very recent versions of Solaris
- Guest Additions: added a heartbeat service (see the manual for more information)
- Linux hosts / guests: support for Linux distributions using systemd without sysv emulation (e.g. ArchLinux)
- Windows Additions/WDDM: improved video memory utilization and allow more/bigger guest screens with large resolutions (including HiDPI)
- Linux Additions: added -s parameter to mount.vboxsf to be sloppy with invalid parameters
- X11 Additions: fixed wrong DPI value
- Mac OS X guests: limit the CPU family for legacy guests
- Solaris Additions: added quiesce support to co-operate with Solaris' fast-reboot feature

* VMM: fixed a problem with large pages in Hyper-V
* VMM: when using the KVM PV provider, use the same frequency for all VCPUs. This will fix slow boots on certain hosts.
* VMM: fixed a hang under certain conditions for SMP guests (32-bit hosts only)
* VMM: several fixes
* AHCI: fixed a crash during shutdown under rare conditions
* AHCI: fixed crash as a result of I/O errors in certain conditions
* Audio: fixed a VM hang with the ALSA backend with certain ALSA configurations
* VGA: fixed loading of saved state if 2D Video Acceleration is enabled
* GUI: apply user interface settings from corresponding page only after pressing OK, not instantly on-the-fly
* GUI: remember size-hints and enabled/disabled states for secondary guest-screens in multi-screen setups on VM restart
* Drag and drop: various fixes for KDE-based guests
* Drag and drop: added transferring plain text to Windows guests
* Drag and drop: fixed transferring large files from host to Linux/Unix guests
* Guest Control: several fixes
* Mac OS X hosts: El Capitan fixes
* Additions/Linux: added -s parameter to mount.vboxsf to be sloppy with invalid parameters

- VMM: fixed a GP in SUPR0QueryVTCaps
- VMM: fixed a raw mode bug (5.0.0 RC1 regression)
- xHCI: fixed resuming from a saved state
- USB: improve playback with USB sound devices attached to the emulated OHCI controller
- Audio: provide Linux guests a different AC97 audio codec type so Linux ALSA doesn't mis-detect the link speed (default for new VMs)
- Drag and drop: enabled guest to host support for OS X hosts
- Drag and drop: fixed freezes and crashes in some error cases
- API: OS type description consistency fix
- API: fixed a check which prevented changing the network promiscuous mode at runtime
- API: don't keep OVA files open after import
- API: don't resume a VM on host-resume unless it was previously paused due to a host-suspend
- API: don't lose the saved state and "current state changed" flag during cloning of a VM
- ExtPack: don't fail if the TMP directory contains non-latin1 characters
- Mac OS X hosts: don't crash when upgrading from VBox 4.3.28 which has a bug in handling the CR4.VMXE bit
- Solaris hosts: Solaris 12 installer fix
- X11 Additions: fixed wrong DPI value

- GUI: NLS fixes. NLS strings are now frozen.
- GUI: Improved HiDPI support for Windows host, icons/size-hint adjustments.
- GUI: Use fast scaling mechanism for integer scale-factors .
- Separate UI/VM: fixed completely broken re-attaching to a headless VM.
- Drag and drop: fixed hang when reporting host errors such as inaccessible (locked) files.
- PCNet: OpenStep fix
- Host-only networking: an attempt to fix some VERR_SUPDRV_COMPONENT_NOT_FOUND problems
- NAT: Don't forcibly reset/drop all connections when link goes down
- AHCI: fixed a possible hand during VM shutdown
- Audio: fix audio output if the default output device changes, before this fix it would always stream to the output device being the default when the VM was started
- VBoxSVC: don't keep the support driver permanently open
- VBoxManage addencpassword: read the command line from the console or from a file
- vbox-img: added resize command
- X11 Additions: fix for X.org servers with RandR 1.1

* VMM: some XSAVE fixes (e.g. here)
* GUI: hot-plugging support for USB storage controller.
* GUI: fixed icons for savestate/restorestate and some of icons for HiDPI aware Win/X11 hosts.
* NAT: don't kill UDP bindings on ICMP errors
* Drag and drop: various bugfixes for Linux hosts and guests
* Encryption: fixed cloning VMs
* Audio: Fixed volume control for mono streams
* Audio/SB16: Fixed loss of output after loading saved state.
* USB3: fixed attaching multiple emulated disks to the xHCI controller
* 3D: fixed a crash on restoring the VM state
* Snapshots: fixed Beta 3 regression
* VBoxManage: fixed reading the partition table on Windows
* iSCSI: fixed a hang during power off if the initiator connects to the target over the internal network

# The following items were fixed and/or added:
* VMM: fixed a Guru Meditation when rebooting certain guests (for example Solaris doing fast reboot) by fixing the implementation for INIT IPI
* VMM: added some information for diagnosing rare VERR_VMX_INVALID_VMXON_PTR Guru Meditations (VT-x only)
* GUI: HID LEDs sync: prevent synchronization if VM window has no focus (Windows and Mac OS X hosts only)
* GUI: fixed drag and drop moving the cursor between guest screens on certain hosts
* 3D: fixed a crash on restoring the VM state on X11 hosts
* 3D: fixed a crash on Linux guest shutdown
* VRDP: fixed incompatibility with rdesktop 1.8.3
* VRDP: fixed listening for IPv6 on some systems
* Storage: don't crash if creating an asynchronous I/O context fails (e.g. when starting many VMs) and show a proper error message
* Floppy: several fixes
* Audio: improved the behavior of the volume control for the HD audio device emulation
* USB: increase the number of supported drivers from 3 to 5 (Windows hosts only)
* PS/2 keyboard: synchronize the LED state on VM restore (Windows and Mac OS X hosts only)
* NAT Network: when running multiple NAT networks with multiple VMs, only stop the respective services when stopping VMs
* NAT: don't kill UDP bindings on ICMP errors
* NAT: bandwidth limit now works properly with NAT
* BIOS: fixed the returned size value of the VBE 2.0 PMI function 0Ah (4.2.0 regression)
* Guest Control: fixed parameter quoting in Windows guests
* Webcam passthrough improvements for Linux (V4L2) hosts to support more webcam models
* API: don't fail starting a VM with VBOX_E_INVALID_OBJECT_STATE under certain conditions
* API: be more verbose on VBOX_E_INVALID_OBJECT_STATE if a medium is attached to a running VM
* API: fixed a bug which could result in losing certain screen resize events with multi-monitor guests
* rdesktop-vrdp: fixed path to the keymaps
* rdesktop-vrdp: switch to version 1.8.3
* Windows hosts: more hardening fixes
* Linux hosts: another fix for activated SMAP on Linux 3.19 and newer (Broadwell and later)
* Linux hosts: Linux 4.1 compile fix
* Solaris hosts: fixed using of VNIC templates with Crossbow based bridged networking to be compatible with vanity interface names
* Mac OS X hosts: fixed crash during VM termination under rare circumstances
* Windows Additions/WDDM: improved video memory utilization and allow more/bigger guest screens with large resolutions (including HiDPI)
* X11 Additions: prevent flickering when updating mouse cursor
* Solaris Additions: fixed incorrect usage of 'prtconf' while installing Guest Additions (Solaris 10 only)