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How do I cancel an IRP that another thread may be completing at the same time?

Let's say that you allocated a PIRP and sent it down your device stack. You free the PIRP in the completion routine and then return STATUS_MORE_PROCESSING_REQUIRED. To make life more fun, you decide that you want to be able to cancel the sent IRP after Read More...
Posted Sunday, June 29, 2008 11:16 PM by doronh | 1 Comments
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What should you change in a sample before you ship it?

I was going to write about how to do this, but the awesome folks at WHDC got to it before I did.  I did get to review it before it was published, so I did have some influence in what is in the tip ;). So on this one my job is easy, just go read the Read More...
Posted Wednesday, April 23, 2008 11:41 AM by doronh | 0 Comments
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The WDF 1.7 cointstallers are now available

After a long wait (thank you for your patience!), the WDF 1.7 coinstallers are now up on the connect site. To get the bits go to http://connect.microsoft.com Log in using your passport account Navigate to the WDF page (I don't know where it lives in the Read More...
Posted Thursday, April 17, 2008 4:20 PM by doronh | 0 Comments
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Debugger commands (.step_filter) that make my life easier

This is a pretty cool and somewhat obscure debugger command.  It allows you to tell the debugger what functions to skip if you are using the trace command ('t').  I think of the trace command as the 'step into' command though, but that is just Read More...
Posted Wednesday, April 16, 2008 4:02 PM by doronh | 0 Comments
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EvtDevicePreprocessWdmIrp is not entirely free

One of the WDM escapes in KMDF is EvtDeviceWdmIrpPreprocess (or EvtDevicePreprocessWdmIrp in the API in which you register it) which you can register for by calling WdfDeviceInitAssignWdmIrpPreprocessCallback .  This function allows you to process Read More...
Posted Wednesday, April 02, 2008 2:14 PM by doronh | 0 Comments
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Using KeAcquireSpinLockAtDpcLevel is only a perf gain if you know you are DISPATCH_LEVEL

Well, that is certainly a long title ;). First, let us look at an approximate implementation of KeAcquireSpinLock and KeRaiseIrql (and yes I know that KeRaiseIrql is really a #define to KfRaiseIrql, but it is the same thing that happens in the end…) KIRQL Read More...
Posted Friday, March 28, 2008 3:42 PM by doronh | 0 Comments
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Inconceivableable

I have no idea who created the name for PNP_DEVICE_NOT_DISABLEABLE, but I probably have the same reaction as you ... "seriously? that is what they named?" I mean come on, I think it could have at least been named PNP_DEVICE_CANNOT_BE_DISABLED. I am sure Read More...
Posted Tuesday, March 18, 2008 4:55 PM by doronh | 1 Comments
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Once not disableable, forever not disableable

One interesting quirk about the PNP_DEVICE_NOT_DISABLEABLE state is that once it has been set and the PnP manager has processed it, the state is sticky.  By sticky I mean that even if you attempt to clear this bit on a subsequent IRP_MN_QUERY_PNP_DEVICE_STATE Read More...
Posted Tuesday, March 18, 2008 8:21 AM by doronh | 1 Comments
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Returning failure from DriverEntry

One thing that is easily overlooked about implementing DriverEntry is that upon return !NT_SUCCESS, DriverUnload is not called. I mentioned this anecdotally in a previous post , but it is worth expanding on. I was bit by this oversight when I was working Read More...
Posted Monday, March 17, 2008 4:56 PM by doronh | 0 Comments
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one of the books that started it all...

During my sophomore year at Cal Poly , I decided that I wanted to learn about threads, synchronization techniques and other topics associated modern operating systems. Windows 95 had made its debut (yes, it is not a modern OS, but I didn't know that at Read More...
Posted Wednesday, March 12, 2008 8:38 AM by doronh | 1 Comments
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Getting 64 bit Vista to open my Inbox the way I want it to

A bit over a year ago I had to figure out why my Mail key started behaving differently on Vista vs XP and wrote about how I fixed it.  Well, my dev box was so slow that I was able to employ enough sympathy that I got a new one.  While my old Read More...
Posted Tuesday, March 11, 2008 4:00 PM by doronh | 1 Comments
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A must have book for any Windows developer

I saw a book, Advanced Windows Debugging , in the Microsoft company store and quickly read through it. It looked pretty awesome in the level of detail and breadth that it covered. I ordered my own copy and I think it would be an invaluable resource for Read More...
Posted Wednesday, December 19, 2007 10:21 AM by doronh | 4 Comments
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Device installation on Vista failing when it used to work?

There is a hotfix for setupapi.dll, read the KB article http://support.microsoft.com/kb/937187 and see if it applies to your machine Read More...
Posted Wednesday, November 21, 2007 2:55 PM by doronh | 8 Comments

Why I should not be writing applications ;)

The first driver I owned when I started at Microsoft in 1997 was i8042prt.sys, the driver that controls your PS2 mouse and keyboard. I had the job of upgrading it from an NT4 legacy style driver to a PnP enabled Windows 2000 driver. Of course my dad asked Read More...
Posted Friday, November 09, 2007 11:12 AM by doronh | 5 Comments
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How to share HW resources with another driver not in the same PnP hierarchy

First, I have to say that I don't agree with this design pattern at all . I think it leads to too many problems and complications that are not worth the pain. The only reason I am writing this entry is that I have seen so many people get this wrong or Read More...
Posted Wednesday, October 24, 2007 3:56 PM by doronh | 1 Comments
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