[plt-scheme] SQLite

From: Andrew Gwozdziewycz (apgwoz at gmail.com)
Date: Wed Jan 31 17:40:19 EST 2007

Actually, I don't think either of us are "exactly" right.

I actually did a bit more research in this. Traditional mach requires  
other "servers" on top of it to provide resources. Therefore, it's  
possible to run mach with a linux "server", a freebsd "server" all at  
the same time, at least theoretically. The "compatibility layers"  
that i was refering too are the "servers." What I didn't realize is  
that XNU (the OS X kernel) merges mach and the bsd server together to  
form a more cohesive unit. NOT in the traditional mach sense.

The bug referenced previously is however still valid.

On Jan 31, 2007, at 3:57 PM, gregory.woodhouse at sbcglobal.net wrote:

> I don't think that's exactly right. Mach is a microkernel based  
> system developed at Carnegie Mellon that (to the best of my  
> knowledge) just covers process and memory management. It's not a  
> full OS. Steve Jobs was actually behind another product (the NeXT  
> box) that was Mach based, though not nearly the commercial success  
> that OS X was to become. Interestingly, I was first introduced to  
> Scheme by a housemate who actually had a NeXT cube -- I was  
> jealous! Anyway, to form a complete system, a layer needs to be  
> built on top of the microkernel, and OS X uses a FreeBSD emulation  
> layer. In other words, it isn't really FreeBSD, but rather a Mach  
> based OS that supports an interface similar (I don't know enough to  
> say how far the similarity goes) to FreeBSD. I don't think the  
> decision to use Mach has anything to do with POSIX compliance,  
> except insofar as supporting the FreeBSD layer supports POSIX  
> compliance. POSIX is, of course, the portable operating system  
> interface standard, and it really applies to all flavors of Unix/ 
> Linux (some of which are fully compliant and some of which are not).
> I've actually never worked with FreeBSD itself (though I originally  
> learned about Unix using  Version 7, followed by BSD 4.2 and 4.3).  
> I've thought about installing FreeBSD separately (maybe under  
> Parallels?) buty never found any compelling reason to.
> ===
> Gregory Woodhouse
> "Mathematics is the science of patterns."
> --Lynn Arthur Steen, 1988
> ----- Original Message ----
> From: Andrew Gwozdziewycz <apgwoz at gmail.com>
> To: plt-scheme at list.cs.brown.edu
> Sent: Wednesday, January 31, 2007 4:04:16 AM
> Subject: Re: [plt-scheme] SQLite
> On Jan 30, 2007, at 4:37 AM, Hans Oesterholt-Dijkema wrote:
>> There must be something like ldconfig (like linux uses)
>> for MacOS X. Otherwise, the OS itself would have to hardwire
>> stuff and if I remember well, MacOSX is a derivative of
>> (free)bsd?
> MacOSX is NOT a derivative of freeBSD. OSX is built on top of
> the Mach Microkernel, which allows "compatibility layers" to be
> created on top of it. Therefore, OSX provides a FreeBSD
> "compatibility layer" on top of the Mach Microkernel to take advantage
> of POSIX standards.
> This however does not always translate into correct results. For  
> instance
> take a look at Amit Singh's challenge from 2005:
> http://www.kernelthread.com/mac/challenge/result/ where it's  
> discovered
> that a kernel panic can occur by creating a mach_task which then  
> creates
> a new thread. However since the call wasn't created by exec() or  
> fork() an
> important field is not set that tries to be referenced. It wasn't  
> set because
> it can't be set because mach doesn't know how or why a layer above it
> needs something like this set. It doesn't care, but "FreeBSD" of  
> course
> does.
> --
> Andrew Gwozdziewycz
> apgwoz at gmail.com
> http://and.rovir.us  |  http://www.photub.com
> _________________________________________________
>   For list-related administrative tasks:
>   http://list.cs.brown.edu/mailman/listinfo/plt-scheme

Andrew Gwozdziewycz
apgwoz at gmail.com
http://and.rovir.us  |  http://www.photub.com

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