[ros-kernel] How to get started writing ReactOS drivers

[Richard Campbell]

I have a simple answer:

www.osronline.com


Vizzini wrote:

>I just got an e-mail from someone off-list about how to get started
>writing drivers, and I thought I'd copy my response to this list in case
>anyone else out there in TV land has the same question.
>
> -Vizzini
>
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>>I was wondering, how do you plan to do (or already do) device driver 
>>development for ReactOS.
>>I guess using MS DDK is not a very "free" option...
>>    
>>
>
>We have people who use both the DDK and the ReactOS build environment. 
>In general, the code is almost completely compatible (with a couple of
>exceptions, noted below), and the binaries are 100% compatible.  The
>build systems are not compatible, however, so you do have to either pick
>one or go out of your way to support both.
>
>The DDK method is exactly as it is for normal Windows driver
>development.  You create a SOURCES file and copy in a Makefile.  Do your
>coding, run build, and get a .sys file in the end.  This sys file can be
>copied onto your reactos disk, and once you edit the registry to create
>the SCM entry (just like windows, too), the driver will load and run.  
>
>The other method is using the ReactOS source tree.  The easiest way is
>to start with a Makefile and .rc file from another driver in the
>reactos/drivers/ directory.  The whole system runs off of standard GNU
>make, rather than  using build and/or nmake.  You must use a ReactOS
>Makefile, though, which collides with the Makefile that build expects
>from the DDK.  To get around this, you can name your makefile
>GNUmakefile, so you can have both files in the same directory if you
>choose to support both build environments.  MinGW make will only look at
>GNUmakefile, if it exists.
>
>In practice, I usually support both, as it's critical to develop and
>test drivers under Windows 2000/XP/2003, including running under
>Verifier and running Prefast.  This ensures that if there are any
>compatibilities between the ReactOS kernel and the Windows kernel, they
>will be found.
>
>One minor legal point - I don't think it's legal to distribute a binary
>driver built from the Windows DDK for use with ReactOS.  You can
>distribute the SOURCES and Makefile files, though, and you can build and
>test with the DDK yourself, so this isn't really an issue.
>
>As far as source code compatibility goes, Microsoft's CL.EXE supports
>some extensions that our compiler (MinGW GCC) doesn't.  In particular,
>there is no support for SEH constructs, including __try, __except, and
>__finally.  If you call ProbeForRead(), ProbeForWrite(),
>MmProbeAndLockPages(), ZwClose(), or anything else that can throw an
>exception, you have to surround the SEH stuff with 
>
>#if MSC_VER
>#endif
>
>Inline ASM syntax is different (MS uses Intel syntax, whereas GCC
>expects AT&T), and include paths are parsed differently (backslash vs
>forward slash).  File names are case-sensitive on UNIX, of course, as
>well.  Also, declarations like __stdcall are a little different.  See an
>example driver for details.  Finally, many (all?) DDK headers use a
>compiler switch to force the default calling convention to stdcall.  We
>do not, however, so you have to be careful to actually define any
>callbacks that need to be stdcall in the proper wya.
>
>I have ported a few of my own drivers to build in the native ReactOS
>environment, and in no case has it taken me more than a few hours.  
>
>Our kernel is fairly complete, but generally windows drivers are missing
>a few imports on ReactOS.  This is where you go from being a driver
>developer to a kernel developer. ;-)  If you find that some kernel
>functionality is missing, I would encourage you to dive in and take a
>shot at coding it up.
>
>There is one major caveat to the above:  our kernel does not support PnP
>or Power Management just yet.  It is being actively worked on, but so
>far, WDM drivers that expect PnP notifications won't work without some
>special work on your part.  If PnP is a project you'd like to chip in
>on, let me know, and I'll set you up with the guys who are working on it
>now.  I'm sure they'd appreciate the help.
>
>What sorts of drivers are you interested in working on?  I like to try
>to keep a general idea of what is going on in the kernel, so if you do
>decide to venture out on a project, drop me a note.
>
>Best of luck, and don't hesitate to let me know if you have questions or
>need help.  Also, come by #reactos on irc.freenode.net - there are
>usually people there (myself included) that can help.
>
>
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