Windows System Software -- Consulting, Training, Development -- Unique Expertise, Guaranteed Results

Before Posting...
Please check out the Community Guidelines in the Announcements and Administration Category.

MDL system address always mapped

Alex_GrigAlex_Grig Member Posts: 3,238
I noticed that in Win2008 R2, the MDLs I get in my stor miniport do always have the buffer mapped to system space. I then examined the MDL at classpnp!ServiceTransferRequest and the MDL is already mapped there. I suspect the mapping adds unnecessary overhead to the IO. Is there an explanation for that behavior? I'll check Win2008 and Win2003 to see if they are different.

These IRPs are for non-cached, raw disk IO.


  • Alex_GrigAlex_Grig Member Posts: 3,238
    Answering that, I suspect x64 Windows has the whole RAM mapped at all times to the system space, and if the MDL only covers one page, the mapping is present in MDL from the beginning.
Sign In or Register to comment.

Howdy, Stranger!

It looks like you're new here. If you want to get involved, click one of these buttons!

Upcoming OSR Seminars
Developing Minifilters 29 July 2019 OSR Seminar Space
Writing WDF Drivers 23 Sept 2019 OSR Seminar Space
Kernel Debugging 21 Oct 2019 OSR Seminar Space
Internals & Software Drivers 18 Nov 2019 Dulles, VA