Programmatically setting a registry key in "other driver's" hardware key

Hello,

I need a way to programmatically set a registry key in a foreign
driver's hardware registry key.

What do I mean? I need to use IOCTL_INTERNAL_PARALLEL_CONNECT_INTERRUPT
for a parallel port. On W2K and later, this IOCTL fails if
HKLM\SYSTEM\CurrentControlSet\Enum\ACPI\PNP0401\4&5b55c8&0\Device
Parameters\EnableConnectInterruptIoctl is not set to 1 (or PNP0400\...
in case of a non-ECP parallel port)

Until now (development), I'm setting this value by hand. Anyway, for
production, I want to change this setting programmatically.

Unfortunately, I found some more sophisticated parallel port cards do
not have a hardware key on ACPI\PNP040x, but on
HKLM/..../MF/PCI#VEN_131F&......./*/Device Parameters
or
HKLM\SYSTEM\CurrentControlSet\Enum\VSCOMBUS\BUS_0000&DEV_000B&FUN_0000\0000\Device Parameters
HKLM\SYSTEM\CurrentControlSet\Enum\VSCOMBUS\BUS_0000&DEV_000B&FUN_0000\0001\Device Parameters

Now, I ask myself how I could find out programmatically where these are
located? I have searched the DDK Help, but I have not been able to find
the appropriate call. I thought about IoGetDeviceProperty(), but it does
not seem to help me (or I am totally overlooking something). I found a
function to return the service (software) key. There, on
HKLM\SYSTEM\Currentcontrolset\services\parport\enum\0, I found
ACPI\PNP0400\5&324d5432&0 (for example). Is this what I am searching
for, that is, append this to HKLM\System\CurrentControlSet\Enum? Or do I
have to use another interface?

Any input is appreciated,
Spiro.

 

open up the port you want to send the IOCTL to. send it a PIRP with
IRP_MN_QUERY_DEVICE_RELATIONS / TargetDeviceRelations. This will give you
the PDO for that stack. You can then use IoOpenDeviceRegistryKey and set
the value

http://msdn.microsoft.com/library/d..._94e53086-01ad-4b10-a128-3eae657c5fcc.xml.asp

http://msdn.microsoft.com/library/d..._7b6ab819-56e3-4d4a-956a-51e4a83300f0.xml.asp

beware of wrap. also, i don't know if the LPT driver inspects this value
when the IOCTL is sent or when the stack is initially started. If it is
when it is initially started, you will need to disable and then reenable the
stack (which you can only do from user mode).

d

 

Hello Doron,

[...]

Thank you for your explanation, I will try and report if I had success.

As I have changed this registry value by hand more than once ;-) I found
out that it is checked on each IOCTL, so this is not a problem.

Thank you very much!

Regards,
Spiro.

 

Hello Doron,

Thanks, this works like a charm!

Regards,
Spiro.

 

Hello,

Well, setting the registry key works, but I totally forgot that I have
to do an additional element:

I do not only have to set EnableConnectInterruptIoctl WORD to 1, but I
have also to mimic what is done when a user lets the parallel port
driver use an interrupt in the device manager. I found out that it
essentially sets FilterResourceMethod WORD to 2. Unfortunately, the
driver does not recognize this until a reboot is done, while it does
accept it immediately when this is changed in the device manager.

So, my question is: Can I mimic this? I think I have to let the bus
driver reenumerate the device, this, that it is initialized again. I
thought I could do this with IoInvalidateDeviceRelations(), but this
does not work.

Can anyone give me any hints? It does not matter if this solution is
from user or from kernel mode, anything is highly appreciated. ;-)

Regards,
Spiro.

 

if you can do this in user mode, look at the devcon example for disable and
then reenabling. it could be the property page is sending a
DIF_PROPERTY_CHANGED which i think tears down and builds upt he stack again.

d

 

Hello,

I completely forgot to mention: Your hint was very good, it works as
expected with DIF_PROPERTY_CHANGED.

Thank you,
Spiro.