a bus upper filter must attach to pdo and pdo which both created by the bus driver?

Hi,

I write a filter base on tosterfilter. I would like attach the fido to a bus
driver. And the bus driver create a pdo and a fdo. Should I attach my fido
to the both?

sorry for my bad English .
Any input will be appreciated.

 

A filter driver attaches either above the FDO (an "upper filter") or
between the PDO and FDO (a "lower filter"). The one you need depends on
what your filter is supposed to do.

http://blogs.msdn.com/doronh/archive/2006/02/14/532072.aspx

Bus filters can be tricky. Can you describe what you hope to do in more
detail?

 

Typically, a lower filter driver is between the function driver and
the bus driver, and the FiDO that a lower filter driver creates is
between FDO(created by the function driver) and PDO(created by bus
driver).

If the bus driver creates more than one device objects, the FiDO is
supposed to be attached on the top one. However, there is no need to
care about this. Because your lower filter driver is loaded right
after the bus driver, thus the device object it creates shoud be at
the correct position.