<HTML><BODY style="word-wrap: break-word; -khtml-nbsp-mode: space; -khtml-line-break: after-white-space; "><DIV>Actually, I don't think either of us are "exactly" right.</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>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. </DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>The bug referenced previously is however still valid. </DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV><BR class="khtml-block-placeholder"></DIV><BR><DIV><DIV>On Jan 31, 2007, at 3:57 PM, <A href="mailto:gregory.woodhouse@sbcglobal.net">gregory.woodhouse@sbcglobal.net</A> wrote:</DIV><BR class="Apple-interchange-newline"><BLOCKQUOTE type="cite"><SPAN class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-align: auto; -khtml-text-decorations-in-effect: none; text-indent: 0px; -apple-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><DIV style="font-family:times new roman, new york, times, serif;font-size:12pt; font-family: times new roman; font-size: 16px; "><DIV style="font-family: times new roman; font-size: 16px; "></DIV><DIV style="font-family: times new roman; font-size: 16px; "><SPAN class="Apple-style-span" style="font-family: times new roman; font-size: 16px; ">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).</SPAN></DIV><DIV style="font-family: times new roman; font-size: 16px; "><SPAN class="Apple-style-span" style="font-family: times new roman; font-size: 16px; "> </SPAN></DIV><DIV style="font-family: times new roman; font-size: 16px; "><SPAN class="Apple-style-span" style="font-family: times new roman; font-size: 16px; ">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.</SPAN></DIV><DIV style="font-family: times new roman; font-size: 16px; "><SPAN class="Apple-style-span" style="font-family: times new roman; font-size: 16px; "> </SPAN></DIV><SPAN class="Apple-style-span" style="font-family: times new roman; font-size: 16px; ">===</SPAN><BR style="font-family: times new roman; font-size: 16px; "><SPAN class="Apple-style-span" style="font-family: times new roman; font-size: 16px; ">Gregory Woodhouse </SPAN><BR style="font-family: times new roman; font-size: 16px; "><BR style="font-family: times new roman; font-size: 16px; "><SPAN class="Apple-style-span" style="font-family: times new roman; font-size: 16px; ">"Mathematics is the science of patterns."</SPAN><BR style="font-family: times new roman; font-size: 16px; "><SPAN class="Apple-style-span" style="font-family: times new roman; font-size: 16px; ">--Lynn Arthur Steen, 1988</SPAN><DIV style="FONT-SIZE: 12pt; FONT-FAMILY: times new roman, new york, times, serif; font-family: times new roman; font-size: 16px; "><BR style="font-family: times new roman; font-size: 16px; "><BR style="font-family: times new roman; font-size: 16px; "><DIV style="FONT-SIZE: 12pt; FONT-FAMILY: times new roman, new york, times, serif; font-family: times new roman; font-size: 16px; "><SPAN class="Apple-style-span" style="font-family: times new roman; font-size: 16px; ">----- Original Message ----</SPAN><BR style="font-family: times new roman; font-size: 16px; "><SPAN class="Apple-style-span" style="font-family: times new roman; font-size: 16px; ">From: Andrew Gwozdziewycz <<A href="mailto:apgwoz@gmail.com">apgwoz@gmail.com</A>></SPAN><BR style="font-family: times new roman; font-size: 16px; "><SPAN class="Apple-style-span" style="font-family: times new roman; font-size: 16px; ">To: <A href="mailto:plt-scheme@list.cs.brown.edu">plt-scheme@list.cs.brown.edu</A></SPAN><BR style="font-family: times new roman; font-size: 16px; "><SPAN class="Apple-style-span" style="font-family: times new roman; font-size: 16px; ">Sent: Wednesday, January 31, 2007 4:04:16 AM</SPAN><BR style="font-family: times new roman; font-size: 16px; "><SPAN class="Apple-style-span" style="font-family: times new roman; font-size: 16px; ">Subject: Re: [plt-scheme] SQLite</SPAN><BR style="font-family: times new roman; font-size: 16px; "><BR style="font-family: times new roman; font-size: 16px; "><BR style="font-family: times new roman; font-size: 16px; "><DIV style="font-family: times new roman; font-size: 16px; "><DIV style="font-family: times new roman; font-size: 16px; "><SPAN class="Apple-style-span" style="font-family: times new roman; font-size: 16px; ">On Jan 30, 2007, at 4:37 AM, Hans Oesterholt-Dijkema wrote:</SPAN></DIV><BR class="Apple-interchange-newline"><BLOCKQUOTE type="cite"><DIV style="MARGIN: 0px; color: rgb(0, 0, 221); font-family: times new roman; font-size: 16px; "><SPAN class="Apple-style-span" style="color: rgb(0, 0, 221); font-family: times new roman; font-size: 16px; ">There must be something like ldconfig (like linux uses)</SPAN></DIV><DIV style="MARGIN: 0px; color: rgb(0, 0, 221); font-family: times new roman; font-size: 16px; "><SPAN class="Apple-style-span" style="color: rgb(0, 0, 221); font-family: times new roman; font-size: 16px; ">for MacOS X. Otherwise, the OS itself would have to hardwire</SPAN></DIV><DIV style="MARGIN: 0px; color: rgb(0, 0, 221); font-family: times new roman; font-size: 16px; "><SPAN class="Apple-style-span" style="color: rgb(0, 0, 221); font-family: times new roman; font-size: 16px; ">stuff and if I remember well, MacOSX is a derivative of</SPAN></DIV><DIV style="MARGIN: 0px; color: rgb(0, 0, 221); font-family: times new roman; font-size: 16px; "><SPAN class="Apple-style-span" style="color: rgb(0, 0, 221); font-family: times new roman; font-size: 16px; ">(free)bsd?</SPAN></DIV></BLOCKQUOTE></DIV><DIV style="font-family: times new roman; font-size: 16px; "><BR class="khtml-block-placeholder"></DIV><DIV style="font-family: times new roman; font-size: 16px; "><SPAN class="Apple-style-span" style="font-family: times new roman; font-size: 16px; ">MacOSX is NOT a derivative of freeBSD. OSX is built on top of</SPAN></DIV><DIV style="font-family: times new roman; font-size: 16px; "><SPAN class="Apple-style-span" style="font-family: times new roman; font-size: 16px; ">the Mach Microkernel, which allows "compatibility layers" to be</SPAN></DIV><DIV style="font-family: times new roman; font-size: 16px; "><SPAN class="Apple-style-span" style="font-family: times new roman; font-size: 16px; ">created on top of it. Therefore, OSX provides a FreeBSD </SPAN></DIV><DIV style="font-family: times new roman; font-size: 16px; "><SPAN class="Apple-style-span" style="font-family: times new roman; font-size: 16px; ">"compatibility layer" on top of the Mach Microkernel to take advantage</SPAN></DIV><DIV style="font-family: times new roman; font-size: 16px; "><SPAN class="Apple-style-span" style="font-family: times new roman; font-size: 16px; ">of POSIX standards.</SPAN></DIV><DIV style="font-family: times new roman; font-size: 16px; "><BR class="khtml-block-placeholder"></DIV><DIV style="font-family: times new roman; font-size: 16px; "><SPAN class="Apple-style-span" style="font-family: times new roman; font-size: 16px; ">This however does not always translate into correct results. For instance</SPAN></DIV><DIV style="font-family: times new roman; font-size: 16px; "><SPAN class="Apple-style-span" style="font-family: times new roman; font-size: 16px; ">take a look at Amit Singh's challenge from 2005:</SPAN></DIV><DIV style="font-family: times new roman; font-size: 16px; "><A href="http://www.kernelthread.com/mac/challenge/result/" target="_blank" rel="nofollow"><SPAN class="Apple-style-span" style="color: rgb(0, 0, 238); font-family: times new roman; font-size: 16px; -khtml-text-decorations-in-effect: underline; ">http://www.kernelthread.com/mac/challenge/result/</SPAN></A><SPAN class="Apple-style-span" style="font-family: times new roman; font-size: 16px; "> where it's discovered</SPAN></DIV><DIV style="font-family: times new roman; font-size: 16px; "><SPAN class="Apple-style-span" style="font-family: times new roman; font-size: 16px; ">that a kernel panic can occur by creating a mach_task which then creates</SPAN></DIV><DIV style="font-family: times new roman; font-size: 16px; "><SPAN class="Apple-style-span" style="font-family: times new roman; font-size: 16px; ">a new thread. However since the call wasn't created by exec() or fork() an</SPAN></DIV><DIV style="font-family: times new roman; font-size: 16px; "><SPAN class="Apple-style-span" style="font-family: times new roman; font-size: 16px; ">important field is not set that tries to be referenced. It wasn't set because</SPAN></DIV><DIV style="font-family: times new roman; font-size: 16px; "><SPAN class="Apple-style-span" style="font-family: times new roman; font-size: 16px; ">it can't be set because mach doesn't know how or why a layer above it</SPAN></DIV><DIV style="font-family: times new roman; font-size: 16px; "><SPAN class="Apple-style-span" style="font-family: times new roman; font-size: 16px; ">needs something like this set. It doesn't care, but "FreeBSD" of course </SPAN></DIV><DIV style="font-family: times new roman; font-size: 16px; "><SPAN class="Apple-style-span" style="font-family: times new roman; font-size: 16px; ">does.</SPAN></DIV><BR style="font-family: times new roman; font-size: 16px; "><DIV style="font-family: times new roman; font-size: 16px; "><SPAN class="Apple-style-span" style="WORD-SPACING: 0px; FONT: 12px Helvetica; TEXT-TRANSFORM: none; COLOR: rgb(0,0,0); TEXT-INDENT: 0px; WHITE-SPACE: normal; LETTER-SPACING: normal; BORDER-COLLAPSE: separate; border-spacing: 0px 0px; orphans: 2; widows: 2"><SPAN class="Apple-style-span" style="WORD-SPACING: 0px; FONT: 12px Helvetica; TEXT-TRANSFORM: none; COLOR: rgb(0,0,0); TEXT-INDENT: 0px; WHITE-SPACE: normal; LETTER-SPACING: normal; BORDER-COLLAPSE: separate; border-spacing: 0px 0px; orphans: 2; widows: 2"><SPAN class="Apple-style-span" style="WORD-SPACING: 0px; FONT: 12px Helvetica; TEXT-TRANSFORM: none; COLOR: rgb(0,0,0); TEXT-INDENT: 0px; WHITE-SPACE: normal; LETTER-SPACING: normal; BORDER-COLLAPSE: separate; border-spacing: 0px 0px; orphans: 2; widows: 2"><DIV>--</DIV><DIV>Andrew Gwozdziewycz</DIV><DIV><A href="mailto:apgwoz@gmail.com" target="_blank" rel="nofollow"><SPAN class="Apple-style-span" style="color: rgb(0, 0, 238); -khtml-text-decorations-in-effect: underline; ">apgwoz@gmail.com</SPAN></A></DIV><DIV><A href="http://and.rovir.us/" target="_blank" rel="nofollow"><SPAN class="Apple-style-span" style="color: rgb(0, 0, 238); -khtml-text-decorations-in-effect: underline; ">http://and.rovir.us</SPAN></A> | <A href="http://www.photub.com/" target="_blank" rel="nofollow"><SPAN class="Apple-style-span" style="color: rgb(0, 0, 238); -khtml-text-decorations-in-effect: underline; ">http://www.photub.com</SPAN></A></DIV><DIV><BR class="khtml-block-placeholder"></DIV><BR class="Apple-interchange-newline"></SPAN></SPAN></SPAN></DIV><BR style="font-family: times new roman; font-size: 16px; "><DIV style="font-family: times new roman; font-size: 16px; "><SPAN class="Apple-style-span" style="font-family: times new roman; font-size: 16px; ">_________________________________________________</SPAN><BR style="font-family: times new roman; font-size: 16px; "><SPAN class="Apple-style-span" style="font-family: times new roman; font-size: 16px; "> For list-related administrative tasks:</SPAN><BR style="font-family: times new roman; font-size: 16px; "><SPAN class="Apple-style-span" style="font-family: times new roman; font-size: 16px; "> </SPAN><A href="http://list.cs.brown.edu/mailman/listinfo/plt-scheme" target="_blank"><SPAN class="Apple-style-span" style="color: rgb(0, 0, 238); font-family: times new roman; font-size: 16px; -khtml-text-decorations-in-effect: underline; ">http://list.cs.brown.edu/mailman/listinfo/plt-scheme</SPAN></A></DIV></DIV><BR style="font-family: times new roman; font-size: 16px; "></DIV></DIV><BR class="Apple-interchange-newline"></SPAN></BLOCKQUOTE></DIV><BR><DIV> <SPAN class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-align: auto; -khtml-text-decorations-in-effect: none; text-indent: 0px; -apple-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><SPAN class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-align: auto; -khtml-text-decorations-in-effect: none; text-indent: 0px; -apple-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><SPAN class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-align: auto; -khtml-text-decorations-in-effect: none; text-indent: 0px; -apple-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><SPAN class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-align: auto; -khtml-text-decorations-in-effect: none; text-indent: 0px; -apple-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><DIV>--</DIV><DIV>Andrew Gwozdziewycz</DIV><DIV><A href="mailto:apgwoz@gmail.com">apgwoz@gmail.com</A></DIV><DIV><A href="http://and.rovir.us">http://and.rovir.us</A> | <A href="http://www.photub.com">http://www.photub.com</A></DIV><DIV><BR class="khtml-block-placeholder"></DIV><BR class="Apple-interchange-newline"></SPAN></SPAN></SPAN></SPAN> </DIV><BR></BODY></HTML>