Re: Newbie Questions
Re: Newbie Questions
- Subject: Re: Newbie Questions
- From: "Alex Nelson" <email@hidden>
- Date: Fri, 30 Nov 2007 16:31:58 -0800
> I am not completely new to the darwin underpinnings, but I have been
> assigned a task that definitely requires pretty good knowledge of the
> mach kernel. First I'd like to ask what's a good introduction to the
> kernel (let's call it a crash course).
Well, in my opinion there are a number of interesting technical papers on the Mach 3 kernel...that is the version of the mach kernel used in the XNU kernel.
There is an excellent non-technical introduction that is freely available, it is the appendix to the book "Operating System Concepts" (7th ed) by Avi Silberschatz, Peter Baer Galvin and Greg Gagne :
http://codex.cs.yale.edu/avi/os-book/os7/online-dir/Mach.pdfAnother excellent introductory text is "THE MACH SYSTEM":
http://library.nocrew.org/lib/os/Mach.txt
You may wish to consult the documentation, both publications and unpublished works, at the Carnegie Mellon University's Mach page:
http://www.cs.cmu.edu/afs/cs/project/mach/public/www/doc/documents_top.htmlDepending on how in depth you want to get, you can always try reading up on the Mach 3 source code directly (it's unlicensed):
http://www.cs.cmu.edu/afs/cs/project/mach/public/www/sources/sources_top.html> Next I'd like to explain what I need to be able to do. I basically
> need to be able to detect when someone is reading from a shared
> resource (in this case the display buffer). For what I understand,
> any such resources are arbitrated through mach ports. If a process
> needs access to one, it obtains either read or write rights to it
> (multiple reader, single writer?), and then is able to access the
> resource. Is this correct? If so, I should be able to determine
> when someone obtains read access to such a port via the kernel trace
> facility or something similar. At least that's my idea. Perhaps I
> am wayyyyyyy off. Feel free to let me know if that's so or if I am
> oversimplifying things.
Hmm...but wouldn't the display buffer be represented by a file? And using the freeBSD virtual file system to access it, if it's accessed wouldn't the file be locked?
Again, I'm purely guessing, I may be equally way off.
But I'd use the Unix approach and try to work with the file representation of the device.
Cheers!
Alex Nelson
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