January 2012 - Darwin-kernel

Re: Kext ring level
by Shantonu Sen 03 Jan '12

03 Jan '12

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com The kernel is open source, you can build it yourself and add instrumentation to determine these things. None of these things are considered KPI or stable interfaces. Perhaps the Linux kernel might be more interesting for your research. Shantonu On Jan 3, 2012, at 4:00 AM, Quinn The Eskimo! wrote: > > On 27 Dec 2011, at 21:49, José Cornado wrote: > >> In which ring level does a kext run? > > The Darwin kernel does not use the concept of rings. All kernel code runs in supervisor mode, and all user processes run in user mode. On x86 CPUs these map to rings 0 and 3, respectively, but to some extent that's an implementation detail. The kernel has and continues to run on a variety of different CPU architectures, most of which aren't based on rings. > >> Does GDT is memory protected? If so would a kext have access to it? > > What are you planning to do with the GDT? In most cases a KEXT can achieve its memory management goals without having to access the GDT directly, and accessing the GDT directly is likely to result in long-term binary compatibility problems. > > Share and Enjoy > -- > Quinn "The Eskimo!" <http://www.apple.com/developer/> > Apple Developer Relations, Developer Technical Support, Core OS/Hardware > > > _______________________________________________ > Do not post admin requests to the list. They will be ignored. > Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) > Help/Unsubscribe/Update your Subscription: > http://lists.apple.com/mailman/options/darwin-kernel/ssen%40apple.com > > This email sent to ssen(a)apple.com _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… This email sent to site_archiver(a)lists.apple.com

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Re: nlist and stab headers
by José Cornado 03 Jan '12

03 Jan '12

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Re: nlist and stab headers
by Quinn "The Eskimo!" 03 Jan '12

03 Jan '12

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com On 3 Jan 2012, at 13:17, José Cornado wrote: > I thought it was reasonably dated :-} Well, that depends on what you're trying to do. For the most part STABS was replaced by DWARF... well, a long time ago. The nlist format is still relevant if you're parsing Mach-O images, but that's a pretty unusual thing to do in kernel code. Share and Enjoy -- Quinn "The Eskimo!" <http://www.apple.com/developer/> Apple Developer Relations, Developer Technical Support, Core OS/Hardware _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… This email sent to site_archiver(a)lists.apple.com

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Re: nlist and stab headers
by José Cornado 03 Jan '12

03 Jan '12

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Re: memory mapped files risks(?)
by José Cornado 03 Jan '12

03 Jan '12

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Re: memory mapped files risks(?)
by Quinn "The Eskimo!" 03 Jan '12

03 Jan '12

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com On 2 Jan 2012, at 04:07, José Cornado wrote: > Are there any problems with using memory-mapped files to cross boundary (kernel<->user)? There's nothing fundamentally broken about sharing a memory mapped file between the kernel and user space. However, as with all shared mappings, you have to be very careful because: o doing this correctly is difficult, primarily because of the potential race conditions o there are many potential security issues o your kernel code must guarantee to not trigger a page fault on the page fault path This last point is key: keep in mind that all disk and network I/O might potentially be on the page fault path. * * * Perhaps you'd like to post some details of your high-level goal. You've asked a bunch of questions that are very much on the edge of what we support for third party KEXTs. If you can give us more context, we should be able to offer better suggestions. Share and Enjoy -- Quinn "The Eskimo!" <http://www.apple.com/developer/> Apple Developer Relations, Developer Technical Support, Core OS/Hardware _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… This email sent to site_archiver(a)lists.apple.com

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Re: nlist and stab headers
by Quinn "The Eskimo!" 03 Jan '12

03 Jan '12

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com On 31 Dec 2011, at 18:23, José Cornado wrote: > Is there something inherently unsafe about these headers to be outside the kernel framework or are those types defined somewhere else? I'm confused by your question. Why would kernel code want to mess with an obsolete debugging symbols format? Share and Enjoy -- Quinn "The Eskimo!" <http://www.apple.com/developer/> Apple Developer Relations, Developer Technical Support, Core OS/Hardware _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… This email sent to site_archiver(a)lists.apple.com

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Re: Kext ring level
by Quinn "The Eskimo!" 03 Jan '12

03 Jan '12

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com On 27 Dec 2011, at 21:49, José Cornado wrote: > In which ring level does a kext run? The Darwin kernel does not use the concept of rings. All kernel code runs in supervisor mode, and all user processes run in user mode. On x86 CPUs these map to rings 0 and 3, respectively, but to some extent that's an implementation detail. The kernel has and continues to run on a variety of different CPU architectures, most of which aren't based on rings. > Does GDT is memory protected? If so would a kext have access to it? What are you planning to do with the GDT? In most cases a KEXT can achieve its memory management goals without having to access the GDT directly, and accessing the GDT directly is likely to result in long-term binary compatibility problems. Share and Enjoy -- Quinn "The Eskimo!" <http://www.apple.com/developer/> Apple Developer Relations, Developer Technical Support, Core OS/Hardware _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… This email sent to site_archiver(a)lists.apple.com

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memory mapped files risks(?)
by José Cornado 02 Jan '12

02 Jan '12

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