TheMSsForum.com >> Drivers >> Mirror Drv, EngDeviceIoControl problem

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Hi,

I am writing a mirror display drive, I am tring to communicate between =
the Display driver and the miniport driver using EngDeviceIoControl, BUT =
of some strange reason when the mimiport gets the HwStartIO request =
'RequestPacket->OutputBuffer' has a pointer different then the one =
passed through the EngDeviceIoControl call, when the EngDeviceIoControl =
returns ( after the MirrorStartIO took place ) the content of the Output =
buffer doesn't change ( although it was update in the Miniports =
HwStartIO request ). What may cause this problem?

The Display Driver code:
****************************

DHPDEV DrvEnablePDEV( .... )
{
...
DWORD dwDataPtr=3D 0;
DWORD dwRetBytes =3D 0;
DWORD dwRet =3D EngDeviceIoControl( hDriver, IOCTL_MIRROR_GET_SHM, NULL, =
0, &dwDataPtr, sizeof(dwDataPtr), &dwRetBytes);
...
}

The miniport code:
*********************

UserModeMem_t g_SharedMemory =3D { 0 };

BOOLEAN MirrorStartIO(
PVOID HwDeviceExtension,
PVIDEO_REQUEST_PACKET RequestPacket
)
{
VideoDebugPrint((Trace,"StartIO Called.\n"));

switch(RequestPacket->IoControlCode)
{
case IOCTL_MIRROR_GET_SHM:
VideoDebugPrint((Trace,"IOCTL_MIRROR_GET_SHM =3D=3D =
RequestPacket->IoControlCode.\n"));
RequestPacket->StatusBlock->Status =3D NO_ERROR;
*(unsigned long*)RequestPacket->OutputBuffer =3D (unsigned =
long)&g_SharedMemory;
RequestPacket->OutputBufferLength =3D sizeof(&g_SharedMemory);
break;
}

return TRUE;
}

Thanks,
Nadav.

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<BODY>
<DIV>
Hi, I am writing a mirror display =
drive, I am=20
tring to communicate between the Display driver and the miniport driver =
using=20
EngDeviceIoControl, BUT of some strange reason when the mimiport gets =
the=20
HwStartIO request 'RequestPacket->OutputBuffer' has a pointer =
different then=20
the one passed through the EngDeviceIoControl call, when the =
EngDeviceIoControl=20
returns ( after the MirrorStartIO took place ) the content of the Output =
buffer=20
doesn't change ( although it was update in the Miniports HwStartIO =
request ).=20
What may cause this problem?
The Display Driver=20
code: ****************************
DHPDEV DrvEnablePDEV( .... =
) { ... DWORD=20
dwDataPtr=3D 0; DWORD dwRetBytes =3D 0; DWORD dwRet =3D=20
EngDeviceIoControl( hDriver, IOCTL_MIRROR_GET_SHM, =
NULL, 0,=20
&dwDataPtr, sizeof(dwDataPtr), =
&dwRetBytes); ... }
 
The miniport=20
code: *********************
UserModeMem_t g_SharedMemory =3D { 0 };
BOOLEAN MirrorStartIO(    =
PVOID=20
HwDeviceExtension,    PVIDEO_REQUEST_PACKET=20
RequestPacket    =
) {  VideoDebugPrint((Trace,"StartIO=20
Called.\n"));
 switch(RequestPacket->IoControlCode)  { &nbs=
p;case=20
IOCTL_MIRROR_GET_SHM:   VideoDebugPrint((Trace,"IOCTL_MIRROR=
_GET_SHM=20
=3D=3D=20
RequestPacket->IoControlCode.\n"));   RequestPacket->S=
tatusBlock->Status =3D=20
NO_ERROR;   *(unsigned =
long*)RequestPacket->OutputBuffer =3D=20
(unsigned=20
long)&g_SharedMemory;   RequestPacket->OutputBufferLe=
ngth =3D=20
sizeof(&g_SharedMemory);   break;  }
 return TRUE; } 
Thanks,    =
Nadav.</DIV></BODY></HTML>

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