From ReactOS

Representation of a GDI driver.

typedef struct _SYSTEM_GDI_DRIVER_INFORMATION
{
  UNICODE_STRING DriverName;
  PVOID ImageAddress;
  PVOID SectionPointer;
  PVOID EntryPoint;
  PIMAGE_EXPORT_DIRECTORY ExportSectionPointer;
  ULONG ImageLength;
} SYSTEM_GDI_DRIVER_INFORMATION, *PSYSTEM_GDI_DRIVER_INFORMATION;

DriverName

Full path of the drivers dll. Example: '\SystemRoot\System32\ATMFD.DLL'

ImageAddress

Pointer to the beginning of the driver mapping.

SectionPointer

Pointer to 'MmLd' Mm load module database.

EntryPoint

Pointer to the drivers entry point.

ImageLength

Size of the DLL in bytes.

typedef struct _LDEV
{ //                                               W2k WXP
  struct _LDEVOBJ *pldevNext;                   // 000 000
  struct _LDEVOBJ *pldevPrev;                   // 004 004
#if (_WIN32_WINNT >= 0x501)
  SYSTEM_GDI_DRIVER_INFORMATION pGdiDriverInfo; // --- 008
#endif
  ULONG            ldevtype;                    // 008 00C
  ULONG            cRefs;                       // 00C 010
  DWORD            dwUnknown1;                  // 010 014
#if (_WIN32_WINNT >= 0x501)
  DWORD            dwUnknown2;                  // --- 018
#else
  SYSTEM_GDI_DRIVER_INFORMATION pGdiDriverInfo; // 014 ---
#endif
  ULONG            ulDriverVersion;             // 018 01C
  ULONG            unk_020;                     //     020 XP: first and last LDEV have 0xFFFFFFFF, other 0x30000
  PFN              apfn[93];                    //     024
  PFN              apfnOrig[93];                //     198
 // size                                               310
} LDEV, *PLDEV; 

pldevNext

Pointer to the next LDEV in the global list. NULL if this is the last LDEVOBJ.

pldevPrev

Pointer to the previous LDEV in the global list. NULL if this is the first LDEVOBJ.

pGdiDriverInfo

Pointer to a SYSTEM_GDI_DRIVER_INFORMATION structure, if the LDEV is associated with a dll file. NULL if the LDEV describes a driver located inside win32k.

ldevtype

Can be one of:

typedef enum
{
  LDEV_DEVICE_DISPLAY = 1,
  LDEV_DEVICE_PRINTER = 2,
  LDEV_DEVICE_META = 3,
  LDEV_DEVICE_MIRROR = 4,
  LDEV_IMAGE = 5,
  LDEV_FONT = 6
} LDEVTYPE;

apfn

Array of pointers to the according driver functions or win32k!WatchDogXxx interceptions.

apfnOrig

The original function pointer that were returned from the driver entry.

Remarks

All LDEVOBJs are kept in a global list. Both structures have the tag 'Gldv' Total size of LDEV is 0x310 Bytes