Add a mini-VDD VxD; revise the INF file and docs

boxv9x.inf

@@ -1,5 +1,5 @@
 ;
-; INF file for VirtualBox Win9x display driver
+; INF file for QEMU Win9x display driver
 ; Copyright 2012-2022, The OS/2 Museum
 
 [version]
@@ -13,17 +13,17 @@ BoxV.Copy = 11
 
 [SourceDisksNames]
 ; BOXV9X is the driver disk volume label
-1="VirtualBox Win9x Display Driver Disk",BOXV9X,1
+1="QEMU Win9x Display Driver Disk",BOXV9X,1
 
 [SourceDisksFiles]
 boxvmini.drv=1
-;boxvmini.vxd=1
+boxvmini.vxd=1
 
 [Manufacturer]
 %Mfg%=Mfg.BoxV
 
 [Mfg.BoxV]
-%PCI\VEN_80EE&DEV_BEEF.DeviceDesc%=BoxV,PCI\VEN_80EE&DEV_BEEF
+%PCI\VEN_1234&DEV_1111.DeviceDesc%=BoxV,PCI\VEN_1234&DEV_1111
 
 [BoxV]
 CopyFiles=BoxV.Copy
@@ -32,7 +32,7 @@ AddReg=BoxV_AddReg
 
 [BoxV.Copy]
 boxvmini.drv
-;boxvmini.vxd
+boxvmini.vxd
 
 [Prev.DelReg]
 HKR,,Ver
@@ -47,7 +47,7 @@ HKR,,DevLoader,,*vdd
 HKR,DEFAULT,Mode,,"8,640,480"
 HKR,DEFAULT,drv,,boxvmini.drv
 HKR,DEFAULT,vdd,,"*vdd,*vflatd"
-;HKR,DEFAULT,minivdd,,boxvmini.vxd
+HKR,DEFAULT,minivdd,,boxvmini.vxd
 ;HKR,DEFAULT,carddvdd,,cardsamp.vxd
 HKR,DEFAULT,RefreshRate,,-1
 HKR,DEFAULT,DDC,,1
@@ -114,5 +114,5 @@ HKR,"MODES\32\1920,1080"
 HKR,"MODES\32\1920,1200"
 
 [Strings]
-Mfg="VirtualBox"
-PCI\VEN_80EE&DEV_BEEF.DeviceDesc="VirtualBox SVGA PCI"
+Mfg="QEMU"
+PCI\VEN_1234&DEV_1111.DeviceDesc="QEMU SVGA PCI"

readdev.txt

@@ -44,8 +44,8 @@ with the overhead of a higher level language.
 
  When built with DBGPRINT (e.g. wmake clean && wmake DBGPRINT=1), the driver
 includes debug logging implemented as dbg_printf() function. This is a small
-printf() subset with output directed to the VirtualBox debug port, such that
-the output appears in the VBox.log file.
+printf() subset with output directed to the QEMU debug port, such that
+the output appears on the debug console (supply "-debugcon stdio" to QEMU).
 
  It would be much nicer to use the C runtime printf(), but that is not at all
 possible because the small model library printf() cannot operate with SS != DS

readme.txt

@@ -1,5 +1,5 @@
 This is a display minidriver for the Windows 9x family of operating systems,
-designed to run on the virtual hardware provided by VirtualBox.
+designed to run on the virtual hardware provided by QEMU ("-device VGA").
 
 The driver can be installed through the Display Settings dialog or through
 the Device Manager.

vxd/.gitignore

@@ -0,0 +1,8 @@
+*.exe
+*.dll
+*.inc
+*.exp
+*.lib
+*.map
+*.obj
+*.vxd

vxd/README.txt

@@ -0,0 +1,13 @@
+To build this VxD, I used the following toolchain, which I can't redistribute:
+
+* ML.EXE (Microsoft Macro Assembler Version 6.11d)
+* LINK.EXE (Microsoft Incremental Linker Version 5.12.8181)
+* MSPDB50.DLL (Needed by the linker; version 6.00.7156)
+
+All three of these binaries came from the Windows 98 DDK, which is available
+on archive.org as a RAR file. The binaries are in BINS_DDK.CAB.
+
+The following header files are also required, also from the Windows 98 DDK:
+
+* VMM.INC (timestamp August 3rd, 1998)
+* MINIVDD.INC (timestamp August 3rd, 1998)

vxd/boxvmini.asm

@@ -0,0 +1,158 @@
+;
+; Mini-VDD VxD for the BOXV9X display driver on QEMU
+;
+; Having this mini-VDD present fixes a couple of problems with the BOXV9X
+; driver. First, it virtualizes accesses to the Bochs VGA registers on I/O
+; ports 1CEh and 1CFh (VBE_DISPI_IOPORT_INDEX and VBE_DISPI_IOPORT_DATA).
+; This means that when you start an MS-DOS Prompt, the screen doesn't go
+; wonky when the DOS VM, calling into the VGA ROM BIOS, ends up trying to
+; perform I/O to those ports.
+;
+; Second, it fixes a problem at Windows shutdown (under KVM and WHPX accel)
+; where the machine hangs instead of showing the "Windows is shutting down"
+; graphic momentarily, and then actually shutting down.
+;
+.386p
+
+.xlist
+include VMM.INC
+include MINIVDD.INC
+.list
+
+Declare_Virtual_Device \
+    BOXVMINI, 4, 0, \
+    MiniVDD_Control, \
+    Undefined_Device_ID, \
+    VDD_Init_Order,,,,
+
+; Data segment
+VxD_DATA_SEG
+
+WindowsVMHandle     dd ?
+
+VxD_DATA_ENDS
+
+; Init segment (discardable)
+VxD_ICODE_SEG
+
+public  MiniVDD_Dynamic_Init
+BeginProc MiniVDD_Dynamic_Init
+;
+    mov WindowsVMHandle, ebx
+;
+    VxDCall VDD_Get_Mini_Dispatch_Table
+    MiniVDDDispatch PRE_HIRES_TO_VGA, PreHiResToVGA
+    MiniVDDDispatch POST_HIRES_TO_VGA, PostHiResToVGA
+    MiniVDDDispatch ENABLE_TRAPS, EnableTraps
+    MiniVDDDispatch DISPLAY_DRIVER_DISABLING, DisplayDriverDisabling
+;
+    mov esi, OFFSET32 MiniVDD_Virtual1CE
+    mov edx, 1ceh
+    VMMCall Install_IO_Handler
+    mov edx, 1ceh
+    VMMCall Disable_Global_Trapping
+;
+    mov esi, OFFSET32 MiniVDD_Virtual1CE
+    mov edx, 1cfh
+    VMMCall Install_IO_Handler
+    mov edx, 1cfh
+    VMMCall Disable_Global_Trapping
+;
+    clc
+    ret
+EndProc MiniVDD_Dynamic_Init
+
+public  MiniVDD_Init_Complete
+BeginProc MiniVDD_Init_Complete
+;
+; At Windows shutdown time, the display driver calls VDD_DRIVER_UNREGISTER,
+; which calls our DisplayDriverDisabling callback, and soon thereafter
+; does an INT 10h (AH=0) to mode 3 (and then 13) in V86 mode. However, the
+; memory ranges for display memory are not always mapped!
+;
+; If the VGA ROM BIOS, during execution of such a set video mode call, tries to
+; clear the screen, and the appropriate memory range isn't mapped, then we end
+; up in a page fault handler, which I guess maps the memory and then resumes
+; execution in V86 mode. But strangely, in QEMU, this fault & resume mechanism
+; does not work with KVM or WHPX assist, at least on Intel. The machine hangs
+; instead (I have not root caused why).
+;
+; We can dodge this problem by setting up real mappings up front.
+;
+; At entry, EBX contains a Windows VM handle.
+;
+    mov edx, 0A0h
+    VMMCall _PhysIntoV86,<edx,ebx,edx,16,0>
+;
+    mov edx, 0B8h
+    VMMCall _PhysIntoV86,<edx,ebx,edx,8,0>
+;
+    ret
+EndProc MiniVDD_Init_Complete
+
+VxD_ICODE_ENDS
+
+; Fixed segment
+VxD_LOCKED_CODE_SEG
+
+Begin_Control_Dispatch MiniVDD
+    Control_Dispatch Device_Init, MiniVDD_Dynamic_Init
+    Control_Dispatch Init_Complete, MiniVDD_Init_Complete
+    Control_Dispatch Sys_Dynamic_Device_Init, MiniVDD_Dynamic_Init
+End_Control_Dispatch MiniVDD
+
+public  MiniVDD_Virtual1CE
+BeginProc MiniVDD_Virtual1CE
+; AX/AL contains the value to be read or written on the port.
+; EBX contains the handle of the VM accessing the port.
+; ECX contains the direction (in/out) and size (byte/word) of the operation.
+; EDX contains the port number, which for us will either be 1CEh or 1CFh.
+    VxDCall VDD_Get_VM_Info
+    cmp edi, WindowsVMHandle    ; Is the CRTC controlled by Windows?
+    jne _Virtual1CEPhysical     ; If not, we should allow the I/O
+    cmp ebx, edi                ; Is the calling VM Windows?
+    jne _Virtual1CEExit         ; If not, we should eat the I/O
+_Virtual1CEPhysical:
+    VxDJmp VDD_Do_Physical_IO
+_Virtual1CEExit:
+    ret
+EndProc MiniVDD_Virtual1CE
+
+public  MiniVDD_EnableTraps
+BeginProc MiniVDD_EnableTraps
+    mov edx, 1ceh
+    VMMCall Enable_Global_Trapping
+    mov edx, 1cfh
+    VMMCall Enable_Global_Trapping
+    ret
+EndProc MiniVDD_EnableTraps
+
+public  MiniVDD_PreHiResToVGA
+BeginProc MiniVDD_PreHiResToVGA
+    mov edx, 1ceh
+    VMMCall Disable_Global_Trapping
+    mov edx, 1cfh
+    VMMCall Disable_Global_Trapping
+    ret
+EndProc MiniVDD_PreHiResToVGA
+
+public  MiniVDD_PostHiResToVGA
+BeginProc MiniVDD_PostHiResToVGA
+    mov edx, 1ceh
+    VMMCall Enable_Global_Trapping
+    mov edx, 1cfh
+    VMMCall Enable_Global_Trapping
+    ret
+EndProc MiniVDD_PostHiResToVGA
+
+public  MiniVDD_DisplayDriverDisabling
+BeginProc MiniVDD_DisplayDriverDisabling
+    mov edx, 1ceh
+    VMMCall Disable_Global_Trapping
+    mov edx, 1cfh
+    VMMCall Disable_Global_Trapping
+    ret
+EndProc MiniVDD_DisplayDriverDisabling
+
+VxD_LOCKED_CODE_ENDS
+end

vxd/boxvmini.def

@@ -0,0 +1,10 @@
+VXD BOXVMINI DYNAMIC
+DESCRIPTION 'DOS386 BOXVMINI Device (Version 4.0)'
+
+SEGMENTS
+        _LTEXT          CLASS 'LCODE'   PRELOAD NONDISCARDABLE
+        _LDATA          CLASS 'LCODE'   PRELOAD NONDISCARDABLE
+        _ITEXT          CLASS 'ICODE'   DISCARDABLE
+
+EXPORTS
+	BOXVMINI_DDB @1

vxd/make.bat

@@ -0,0 +1,7 @@
+@echo off
+
+REM Assemble
+ml -coff -DBLD_COFF -W2 -Zd -c -Cx -DMASM6 -Sg -DVGA -DVGA31 -DMINIVDD=1 -Foboxvmini.obj boxvmini.asm
+
+REM Link
+link /VXD /NOD boxvmini.obj /OUT:boxvmini.vxd /MAP:boxvmini.map /DEF:boxvmini.def