site_archiver@lists.apple.com Delivered-To: darwin-kernel@lists.apple.com Indeed. There are *three* versions of each of the kernel-level headers: * * * * * * And back to your original question... S+E -- Quinn "The Eskimo!" <http://www.apple.com/developer/> Apple Developer Relations, Developer Technical Support, Core OS/Hardware At 21:19 -0800 30/10/06, Rick Mann wrote: This document seems to indicate that sys is available, but when I include <sys/proc.h>, struct extern_proc does not get declared. I can't seem to figure out why not, except perhaps the compiler is including a different file than Command-D is opening up for me. 1. There's the original version in the kernel source code. You can get this from Darwin. This is the version from which the others are derived. 2. There's a user space version in "/usr/include". This has all of the kernel-only stuff preprocessed out. 3. There's a version for third party kernel development in the Kernel framework ("/System/Library/Frameworks/Kernel.framework/Headers"). This has all of the user space stuff preprocessed out. Both 2 and 3 also have all of the implementation details preprocessed out. So, for example, within the kernel we want you to treat the process object as opaque, and thus the <sys/proc.h> in the Kernel framework doesn't have the definition for (struct proc) [1]. The key point here is that, if you're writing code that you want to be binary compatible with future systems, you should only use declarations from 2 or 3 (for user space and kernel code, respectively). These are the things that Apple considers to be API/KPI. When you create a KEXT project in Xcode, Xcode passes magic options to GCC to disable the automatic search of "/usr/include" and to instead search the Kernel framework. And yes, Xcode does have a habit of showing you the wrong file when you use Open Quickly. When doing kernel development, I generally add the Kernel framework to my project, disclose the header list, and type select the relevant header. At 21:00 -0800 30/10/06, Rick Mann wrote: Can I use <sys/proc.h> and extern_proc with current_proc() to get at the pid? You can use a variety of different routines from <sys/proc.h> in the Kernel framework. For example proc_selfpid() or proc_pid(proc_self()). I should caution you that there are circumstances when this won't yield the results you're expecting. For example [2], if you did this on the read/write path of an asynchronous I/O, you might find that proc_self() isn't the process that originally issued the I/O (it's the process that happened to be around when the I/O started). That's the reason why the VFS KPI has a separate vfs_context_t parameter, from which you can derive the original process. [1] This is a simplification. In fact, most of the truly internal stuff has moved to a parallel header. So (struct proc) is actually defined in <sys/proc_internal.h>. [2] With apologies to the /real/ kernel engineers on the list, who know how this stuff actually works. I'm trying to make a pedagogic point here (-: _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel@lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.a... This email sent to site_archiver@lists.apple.com