* Introduction Having successfully built ReactOS and been amazed by what it does, you're now desperate to fill in some of the omissions, this document shows you how. * Prerequisites A working knowledge of NT driver development is useful for understanding the kernel and some of its abstractions. The NT4 ddk is available for free download from http://www.microsoft.com/hwdev/. The Windows 98 and Windows 2000 DDKs are also available but the NT4 one is the most useful. See Legal Stuff below however. There are a number of books on NT driver development, I would recommend 'Windows NT Device Driver Development' (http://www.osr.com/book/) since OSR seem to know their stuff. There is only one book on NT filesystem development 'Windows NT File System Internals'. Please don't buy any of these books unless you need to, and can afford it. These mailing lists and newsgroups are useful for NT internals related questions, ntfsd@atria.com, ntdev@atria.com (subscribe by email to majordomo@atria.com) comp.os.???? microsoft.public.???? * Style There is a coding style used for ReactOS, it's described in a ReactOS's Wiki page called Coding Style: http://www.reactos.org/wiki/index.php/Coding_Style However, not all codebase complies with the rules outlined in that page, so if you need to hack some code which has not been yet formatted, it's wise to keep the kind of formatting it already has, to make it looking good until it receives a formatting patch. * Debugging Debugging kernel-mode code is tricky, these are some snippets DbgPrint writes a message to the console using a printf style format string. The DPRINT macro (defined in internal/debug.h) expands to DbgPrint unless NDEBUG is defined, this is useful for having copious output from a module only when a problem is being debugging. DPRINT also prefixes the message with the file and line number to make it easier to see where output is coming from. DbgPrint can be used at any point including in interrupt handlers. There are options in ntoskrnl/kd/kdebug.c for copying DbgPrint output to a serial device or bochs logging port (parallel support should also be added). This can be useful if a lot of output is being generated. It should be possible to include support for debugging the kernel with gdb over a serial line. Bochs (a shareware CPU emulator) is also useful for debugging the kernel, I wrote some patches to allow capture of console output from within bochs to file and for debugging a kernel running under bochs with gdb. Contact me (welch@cwcom.net) if you're are interested. If CPU reports an exception not handled by the kernel (any page fault not part of virtual memory support or any other exception) the kernel will display output like this and halt General Protection Fault Exception: 13(0) CS:EIP xxxxxxxx:xxxxxxx DS xxxx ES xxxx FS xxxx GS xxxxx EAX: xxxx EBX: xxxx .... EDI: xxxx EFLAGS: xxxx ESP: xxxx cr2: xxxx Stack: xxxx xxxx xxxx ... .... Frames: xxxx xxxx xxxx ... .... The fault type will usually be either 'General Protection' or 'Page Fault', see your Intel manual for the more exotic types. The 'EIP' number is the address of the faulting instruction. If the 'CS' number is 0x20 then the exception occured in kernel mode, if it is 0x11 then the exception occurred in user mode. 'cr2' is the address that the faulting instruction was trying to access, if the exception was a page fault. The number printed after 'Frames' are any addresses on the stack that look like function addresses. If the kernel detects a serious problem that it will bug check, displaying output like this Bug detected (code x, param x x x x) Frames: xxx xxxx xxxx .... Again the numbers printed after 'Frames' are any addresses on the stack that look like function addresss. Usually the kernel will also print a message describing the problem in more detail, the bug check code isn't very useful at the moment. * Contacts There is a mailing list for kernel development, ros-dev@reactos.org The main developers use a svn account to coordinate changes, ask Aleksey (aleksey@reactos.org) for an account if you are going to be adding a lot of code. Smaller patches can go to the mailing list or to the relevant developer (usually the comment at the top of a module will have an email address). Regular snapshots are made available for download, see the mailing list for announcements. * Legal stuff The ReactOS project is GPL'ed, please make sure any code submitted is compatible with this. The NT4 ddk license agreement allows its usage for developing nt drivers only. Legally therefore it can not be used to develop ReactOS, neither the documentation or the sample code. I'm not a lawyer, but I doubt the effiacy of 'shrinkwrap licenses' particularly on freely downloadable software. The only precendent I know of, in a Scottish court, didn't upload this type of license. Also the 'fair use' section of copyright law allows the 'quoting' of small sections from copyrighted documents, e.g. Windows API or DDK documentation