Paged pool memory or Nonpaged pool memory ?? (windows driver development)

Question

Hi all,

I am newbie in windows driver development. I just want to know , a global variable in a driver will use paged pool memory or non paged pool memory ?

Thanks and Regards

Navaneeth

Answer 1

Depends. The Non paged pool should be reserved for memory that must stay in RAM so if you are doing something critical that would affected by a memory page from disk operation then use non paged.

See here for more info.

Looking at this (though it discusses c++ as opposed to C) it would seem that by default the globals can be located in either by #pragma. Also on p22 of this we see how to do this. Finally this discuss here we see that the data segment should be non pagagable by default.

Answer 2

Global variables in a kernel mode driver are allocated from NonPagedPool.

You can also use the device extension (when you call IoCreateDevice), it is always allocated from NonPaged memory.

I hope this helps, Martin