Stealthy, Interesting “Patch Tuesday” Item

The second Tuesday of every month is also known as “Patch Tuesday,” because that’s the day when Microsoft normally releases its security updates, along with other patches and fixes for its various Windows operating systems, applications, and so forth. Yesterday was the second Tuesday in September, and Windows Update proffered 10 items, most of which are described in the Security Bulletin for that month.Here, I’m going to focus in on one non-security update entitled “Update for Windows Vista (KB955302)“.

As anybody who’s been reading my recent blogs knows, I’ve been battling repeated BSODs on my primary production Vista machine lately, at least one third of which have been graphics related. A recent update to a very new Nvidia driver (version 177.83, where I’d been running 175.19 or 177.79) appears to have cured my graphics-related problems, so I was quite naturally interested to see what would be included in this self-professed “reliability and performance update for…Windows Vista SP1.”

Information about Vista Update KB955302

The description of this update is more tantalizing than informative, and mentions nothing about Nvidia graphics.

So I did a little detective work, and started digging into Knowledge Base article KB955302, the document that describes what’s in this update. This includes a description about what updates are included (shown in the next screenshot) that includes the statement “Improvements to the stability of systems on which Nvidia graphics cards are installed.” Given my recent difficulties with that very thing, my interest was definitely engaged here!

 Update details for KB955302

OK, now we’re getting somewhere: ReadyBoost, Wi-Fi, Disk Cleanup, networked communications, and Nvidia are all mentioned.

A little further digging turned up this table of changed system files that includes both dynamic link libraries (DLL file that take a .dll extension) and system files (the .sys extension is sufficiently venerable to trace back to the earliest days of DOS and primarily houses various types of operating system drivers). Obviously, these are important files in general, and crucial to the functions or subsystems they serve. Here’s a snapshot of the files included in this update:

List of files included in the KB955302 download

Detailed file listing for KB955302 contents.

Digging a bit further into the files themselves, here’s what I was able to glean by scouring the Web for more information about where these items fit, and what they do for Windows Vista:

  • Dataclen.dll: related to Disk Space Cleaner for Windows
  • Emdmgmt.dll: part of the Windows ReadyBoost service/environment
  • Cdd.dll: is the canonical display driver that interacts with device-specific graphics drivers
  • Dxgkrnl.sys: DirectX Graphics Kernel
  • Nwifi.sys: Native WiFi Miniport Driver
  • Mrxsmb10.sys: SMB Downlevel subredirector (used for backward compatbilty with System Message Block/SMB communications from older Windows platforms)


It’s pretty obvious that the Nvidia related stuff must reside in Ddd.dll and Dxgkrnl.sys. I can’t say I’ve noticed an overt changes in the behavior of my graphics subsystem since installing this update yesterday, but at least I feel vindicated that my earlier problems were not purely idiosyncratic, and somewhat comforted that Microsoft and Nvidia obviously worked together to get these problems addressed.

I’ve made a couple of calls to Nvidia PR and technical marketing staff, in hopes of obtaining some additional technical details about what’s going on here, and will report what I learn as soon as any such information is forthcoming.

Concluding Unscientific Postscript

I talked to Rick Allen, the PR guy for Nvidia for  Notebook and Video graphics, and he told me that this stability update addresses issues in Microsoft’s own code. Careful re-reading and consideration of their phraseology in “Improvements to the stability of systems on which Nvidia graphics cards are installed” confirms his claims–notice, they don’t assign any responsibility to Nvidia, only indicate that there’s some relationship there. I learned that Nvidia provided some engineering level consulting to Microsoft to help them make the necessary repairs, and also conducted some update testing to make sure that Microsoft got things right. Good on you, Nvidia! I’m glad whatever it was that actually got fixed appears to have made systems with Nvidia cards–like most of mine–more stable.


Leave a Reply

Your email address will not be published. Required fields are marked *