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diff --git a/README.md b/README.md new file mode 100644 index 0000000..d26c58f --- /dev/null +++ b/README.md @@ -0,0 +1,56 @@ +This is a mouse driver for Windows 3.x with VirtualBox mouse integration support. + +I have tested it with Windows 3.0 in real and 386 enhanced modes, as well as Windows 3.11 in 386 enhanced mode. + +# Install + +Just copy vbmouse.drv to your WINDOWS\SYSTEM directory and edit WINDOWS\SYSTEM.INI 's mouse.drv line to point to it, e.g. + + [boot] + mouse.drv = vbmouse.drv + +For a "proper" installation, you may create a floppy image containing oemsetup.inf and vbmouse.drv +and point the Windows Setup program to it when it asks for a 3rd party mouse driver disk. + +# Building + +This requires [http://open-watcom.github.io/](OpenWatcom 2.0), albeit it may work with an older version, +and was only tested on a Linux host. + +The included makefile is a wmake makefile. To build it just enter the OpenWatcom environment and run `wmake vbmouse.drv`. +`wmake flp` may be used to build a floppy image containg oemsetup.inf and vbmouse.drv for easier installation. + +# Design + +This is at its core a driver for a plain PS/2 mouse driver, using the PS/2 BIOS. +If running outside VirtualBox, in fact it will behave like a PS/2 mouse driver. +However, it removes a lot of checks for older platforms and is mostly written in C rather than assembly, +so hopefully it is easier to understand than the Windows sample drivers. + +The VirtualBox guest integrations present itself as a PCI device to the guest. +Thanks to the BIOS, the device is already pre-configured. +The driver uses the real-mode PCI BIOS to request the current configuration of this PCI device. +To communicate with the host, the guest must send the PCI device the (physical) address +of a buffer containing commands to be sent to the host. +The host will write back the response in the same buffer. +Further details are available in [https://wiki.osdev.org/VirtualBox_Guest_Additions](OSDev). +The only challenge here is getting the physical address from inside 386 protected mode Windows, +but turns out this can be done with the `GetSelectorBase()` WINAPI. + +When VirtualBox is told that the guest wants absolute mouse information, VirtualBox will stop sending +relative mouse information via the PS/2 mouse. However, the PS/2 controller will still send interrupts +whenever mouse motion happens, and it will still report mouse button presses. In fact, the only way +to obtain mouse button presses is still through the PS/2 controller. +Thus, the only difference between this driver and a standard PS/2 mouse driver is that, +when an interrupt from the mouse comes in, we won't report the relative mouse motion to Windows. +Rather, we call into VirtualBox (right from the PS/2 BIOS interrupt handler) +to obtain the absolution mouse position, and report that to Windows. + +### Known issues + +Unfortunately, when a MS-DOS old application is foregrounded full-screen, this mouse driver will remain active, +and therefore VirtualBox will not send relative motion data via the PS/2 protocol. +This means full-screen MS-DOS programs will see a PS/2 mouse and will receive button presses from it, but will not +receive mouse motion. The driver would need to deactivative itself in response to a full-screen MS-DOS VM, perhaps +by hooking interrupt 2Fh function 4002h (Notify Foreground Switch) or the like. + |