---
title: WWDC2004 Session 105
framework: wwdc
role: article
path: wwdc/wwdc2004-105
---

# WWDC2004 Session 105

## Transcript

Kind: captions Language: en afternoon my name is kevin van vechten I'm a open source software engineer with Apple I'll be talking today about the core of Mac OS 10 which is known as Darwin it's a BFD layer an old eunuch style it's open source and today I'll be talking a bit about where you can find the sources how you can download them and build them on your own system to make your own customization so first I'd like to talk a little bit about what's new at Apple last year since WWDC we've announced the a psl version to license the majority of the code that Apple develops is released under the apple public source license known as the acs l which was all written OSI approved license in a courtship or open source initiative now it's also a free corefoundation free software license so it's not GPL compatible but it is recognized as a free software licensed by the FSF also we've unified the Apple IDs with our a psl registration so the same Apple ID that you use at your mac com account for itunes music store for apple developer connection can now be used to agree to the license to download these sources and also we had our darwin 701 release which corresponded to mac OS 10.3 panther so at Apple we have several open source projects we dot and we have Darwin streaming server rendezvous header dock the list goes on some really great technology that we have available you should check out on our open source site and the slides that you should check it out at is develop calm / Darwin the one listed up top I don't really like to strongly recommend subscribing to some of the mailing lists at apple com these are lists where members of the community who are interested in open source can discuss various issues they're having and there are also a lot of engineers at Apple who participate on these lists who gives responses to bug reports or general technical questions additionally I'd like to point out open darwin org open darwin org is a mirror of the sources available at Apple and also hosts various other open source projects that are related to Mac os10 such as Darwin ports there's also close collaboration with the think project both of which the URLs are listed here and those two projects bring a large number of third-party open source applications to Mac OS 10 so what you'll learn in this session is what's in Darwin and where you can get it how to build most of the projects that are in Darwin they they tend to follow a common format and we'll go over the best practices for building these sources and also how you can use these projects on a Mac os10 system and I'll specifically i'll be talking about what things are generally safe to replace on mac OS 10 with your own custom iver customized versions and what things you should probably avoid replacing even though they're open source and finally I'll go over a brief outline of how you can make a bootable CD that has Darwin on it which might be useful you know for an open source project might also be useful to come up with some sort of UNIX recovery CD for your own development purposes so Darwin is the open-source core of Mac OS 10 at the lowest level it's the colonel on top of that is iokit libraries and families iokit drivers and finally it's the BFC commands and libraries anything that you have access to from terminal bought app or X term and darwin can be very helpful to you as a developer it's a place to look for reference sample code so for example a lot of the new work you've been hearing about in the past couple days has had to do with the new kernel programming interfaces and finer grained locking in the colonel you can check out the sources to see either the ms-dos FS or webdav FS has an sample of these new locks in use in Tiger and those sources are on the website you can also use these sources to debug your projects you know perhaps it'd be helpful if you added 2k print into the kernel at a certain step because the driver you're riding is having issues it really lets bug from the inside and see both sides of the picture when you're debugging your your programs you can customize your system you know perhaps there's a feature that Apple doesn't provide but there's a patch against parole or against Python or any other open source component it's possible for you to download the sources apply the patch and then get that feature on Mac OS 10 and of course there are also a lot of research opportunities whether you're interested in machine virtualization or or whatever you know there's the ability to to tinker with the the underpinnings of the operating system and try new things out so i'll go over brief history of darwin darwin was first released as a bunch of images of the sources of portions of mac OS 10 server 1.0 and that was over five years ago since then we've had to darwin release that corresponds with each major mac OS 10 release you can notice about halfway down the list there was a break in the numbering from darwin one series to darwin five six and seven we have the darwin versions match the major number in the build number of Mac OS 10 so there's some consistency now you can see you know Mac OS 10.1 had a build number that's started with a five and darwin 5.1 was released answer had a build number that started with the 7 and that's also darwin seven so you can generally match things up using the builds number and the darwin number so you can get darwin from the open source web site the the main link for you know a lot of text on Darwin is developer.apple.com / Darwin which I mentioned earlier but the actual sources live on the WWE open-source apple com server they're also mirrored at darwin source open darwin org we organized the sources by Mac os10 relief so for each least there's a page that has a list of all the open source projects there's the name of the project the license that it's covered under whether it's the Apple public source license or another license and then there's also a tar archive that you can download of those sources so there's also a neat trick for getting all the sources if you if you want to grab them all at once you can go to the open darwin site and they offer anonymous rsync access on the darwin source files so this is an example command up here where it's grabbing all of the sources that correspond to Mac os10 point three point four you could you could change the version number two different Burton and grab them grab those sources instead and the details are available on the open darwin site so now i'm going to talk about building the projects that are in darwin at Apple we have a proprietary build system the 10 build system and it's fairly heavy weight and deals with a lot of issues related to to building Mac OS 10 and a lot of the projects that are in Darwin are customized to be built with this build system unfortunately it's not practical to have this available outside of Apple and so what we'll be talking about is some of the expectations that these projects might have but the 10 build system provides and how you can set you up your environment to build projects in the same manner so before you start it's important to realize that there are a lot of variables involved in building software there's the compiler tool version you have we have GCC 295 GCC 31 33 and now 35 with tiger so it's important to build sources with the the correct set of compiler tools generally speaking the version of the compiler that was used to build a given Mac os10 relief is the same GCC compiler that was shift on that 10 release so for anything in the Panther series of software updates you'll want to use the GCC compiler that came on the developer tools accompanying maco 10.3 it's also important to realize that the environment variables in your shell have a large impact on how things get built there are variables like the sea flags or ldflags which pass extra arguments to the compiler or as linker so if you don't want them to be set to be sure to unset you know any unnecessary variables before building because it can change the results of the build it's also equally important to set the correct environment variables that the project's might be expecting and I'll talk about those in a minute the libraries and headers that you have installed on your system are also important you know that's what the projects are going to link against and so it's always important to keep in mind what versions you have installed on your system and when you're building these projects there they will use those versions so if you are anticipating deploying the project to a different machine you probably want to build on something like 10 dot 3 base and they would have the most compatibility over all the extra software updates if you build on something later like 10 33 or 1030 for it might pick up some changes that may or may not be backward compatible so it's generally speaking easier to be forward compatible than backward compatible the another issue is for example the the file systems with 10.2 i believe it was Deb random was introduced well if you're if you're targeting a piece of software prior to tend to Deb random is going to be there and there's there's not much you can do about it likewise if you're building software for ten two and you're on ten one dev randoms not going to be there so if you have an auto cons configure script that's automatically detecting what features are available it's not going to know that your system your you're targeting should there shouldn't have Deb random it's the system you're on differs so again it's just really important to be building on the same style of system as you want to ultimately use the project on so the overall requirements for building software generally more RAM is better and more disqus better obviously you can you can build sources with less than these requirements but generally speaking having about 300 megabytes of RAM will will keep you from swapping a lot as you're doing large builds and if you if you intend to build a lot of projects that are in Darwin you know I recommend at least two gigabytes of space to work with a lot of the intermediate files during building can take up a lot of space and it's always unfortunate to see a very long compiled I because you ran out of space on Mac OS 10 while you're building is important to have the developer tools installed obviously you'll need those two to have the compiler on the system but it's also important to have the BFC f ck and the x11 f ck installed i think i skipped an item the BFC package on the on the cds i believe it's defaulted to install these days but in the past it may have been an optional install so make sure you have all of your your b SD command line tools because a lot of the sources require those to build properly so another important issue is many of the sources may rely on a case sensitive file system for example the CVS project uses lowercase CVS to denote it be the executable and a lot of the sources but it also is checked into CVS and so there are uppercase CVS directories on the file system because of this is recommended to do all your building on a case sensitive file system whether that's ufs or h fsx and i find that disk images work particularly well for doing this on mac OS 10 on darwin unfortunately disk images aren't available so it will be necessary to use a separate partition shown here is an example command HDI util which will create a 4 gigabyte HFS x volume so that has all the the speed and journaling advantages of h of s but it's also case sensitive by default cause you to build something like the CBS project next I'll talk about the show environment many of the the make files that are used by these sources expect certain environment variables to be set apple's build system sets for very critical environment variables and these are the source route the object route the symbol route and the destination route the source route is simply the absolute path to where the sources are that you are building the object route is a path to what should start out as an empty directory and that is where all the intermediate dotto files and other other miscellaneous intermediate files will be stored during build and will just delete that directory after a build succeeded the symbol route is where debugging versions of any executables libraries or drivers who builds will be placed and those versions have all the symbols and then symbols get stripped out and finally the destination route is the final packaged bits it's possible to take a destination root package it up you with you know a tar archive or something of that nature and then open and then install it on the system that that you want to run the software on it's important to create all these directories before you begin building since some of the make files won't create them and then the building might fail because the directory is missing it's also important to avoid spaces in the past names leading up for these directly do you have spaces and if there's a bug in a make file and it decides it wants to wipe out the object route well you might have some unfortunate consequences so so really be careful and and don't use spaces in these path names finally it's important to change each of these two route wheel ownership that way you get the proper inheritance of the route wheel user ID and group ID in the destination route if you many of the projects only change explicitly the the ownership of files that it expects to be different and so it relies on this default while you're building so when building projects many of the projects have a makefile and if there's a make file you should default to using a new make to project as that's what Apple does if there is a PV projects code file then you'll need to use xcode build which is a command-line tool that can build the d project it's important to always build this route inside indicated some make files will change the ownership or the permissions of the file and the only way to change ownership at least in that would before there are ACL is if you have root privileges so so always be root when you invoke the new make or when you invoke Xcode build and there are two main targets for each of these projects there's an install headers phase I mean install headers phase and spells only the header files so if you have a big library or an i/o kit family and you're missing the headers on your system you don't need to build the entire library to get the headers it's possible to shortcut just do the install headers that will give you the headers you need for that library and then you can move on to the next project that you want to build that requires those headers on the other hand if you use all target it will build the ire binary or library etc and that is a you know the complete package man pages headers and binaries baffle here's the basic environment for the CC tools project now in Mac OS 10 3.4 CC tools is version 4 95.8 and we'd find that just by going to the darwin tar archive so now we can create directories as as each of these variables point to and the sources to CC tools 495 h be in that path that's that's specified or more environment variables that you should set there's a project name which is CC tools there's the project's version designed 58 there's the build which is simply the number of attempts you've made to build this particular course this is our first attempt so it's spilled version the architectures or what architectures you're planning to build for for Mac os10 that's obviously PowerPC Darwin actually supports both 386 architecture at the architecture so you might add in that if you want to the operating system flag for environment variables Mac OS the release should be whatever you're building for so since this is cici tools from 34 you'll want to specify a release Panther for past belief you know 10.0 sweta 10.1 with Puma 10.2 was Jaguar 10.3 panther a 10.4 will figure again the mac OS deployment target will affect how header files are interpreted it should be set to be the version number of the of what you're targeting it shouldn't include a soft state version I believe it should include the major version so 10.1 to 10.3 here 10.4 for Darwin as I mentioned there are a couple of variations you may want to include the i386 architecture while building you may want to include extra cflags for example Darwin does not have the c preprocessor so we're specifying dash no TPP pre-comp so the CPP precompiler doesn't doesn't get run and also the relief is not panther or tiger but the release is simply darwin when building Darwin sources so actually build CC tools we set the environment variables could also pass all the sensors as additional arguments the make command when we're building the sources it's also very useful to redirect all the output to a log file these projects have a lot about put while they're building and if something goes wrong your scroll back and not cover it if it's in a file you can go back and see where things actually started to go wrong so in this example here doing sue dash S which makes everything run its route again that's very important for building the sources we're doing a make install of CC tools PowerPC architecture I show the source route and the additional variables you went over omitted for for brevity the bottom left-hand corner I'm redirecting entered error to standard out so both standards or and standard out will get captured in the same and then I'm storing it in a in a log file that you can see there so I'm going to do a little demo now of going over the step building CC tools that we've just discussed so here i have the command for HDI you tale will create i guess for speed we probably don't need a full two gigabytes so we'll create a disk image quick and this is where we'll be doing our building this is an H fsx disk image so it has case sensitivity so I've chosen a name of build root for this example and I'll change into the bill dude volume now I've already downloaded the CC tool which is so what I'm going to do is extract them into this directory all the courses we publish on the site already have factory name of the project named ash project version so that's already set up you can just extract it to wherever you want to build the sources and you're ready to go so I already have a little script here that's up the appropriate environment variables for source root object root symbol root and desk root it creates the directories to make sure they before the building games and zip to the wheel for each of those and all the environment variables that were discussed and then to the directory where the sources are we make install to build the whole thing and again variables that we had set in the environment we also want to pass as additional argument to make so now we are running his route and all do X which basically tells the bash shell to echo each man said it's running so we can see step by step as we run to the it's ilang CC tools and work on this for a little while now go to this now so now it's the time to about dependencies and back to the build it will fit and there will be an error that streams dot H was not present basically what happens is there's a lot of an aren't shipped on Mac os10 because they're they're not needed for day-to-day use but they are available for the open source web site so right now not easy to determine where the streams dot H file may have come from we're working on some that can help track that type of information down for searching through the Darwin saw you can that there in lib street so the next step would be to go to the open site news project and we want to reprocess for slipstream necessarily need to make the whole black spray we really just need that streams dot H file so it will be sufficient to just do a make stall headers in this particular project we have that we can take the builds result which has we'll call it a route that contains of the built salts of the lid streams installers and we can copy that to the base system on Mac os10 a sudo command is very useful for copying one directory to another so you can just ditto from the directory that contains the live streams headers to slash and that'll copy everything to the correct place if you run a dis route it will offices or what's the permissions always make backups obviously if you're going to be copying this over your based system some can't wrong at times either if you don't have a build of something you're expected you did or versions don't match up so to have good backups if these build on Darwin sydow is not available but but either the ganute are the packs command can be used to copy copy the sources to the roots so I have a couple example usages of both ditto and those packs shown here we're going to go back to the demo to resolve that streams dot H problem that we discussed so we can see here that stream state was not found and we have an install error i also have already downloaded slipstreams fraud so i will extract is now and I have script set up to compile we're doing the same steps setting the source route the object through the symbol route destination route we're creating the directories in case they don't hope we're changing the ownership to route wheel we export the project name in a different building not only do we export them in the environment but also pass them to the make file so in this case that have make install its make install headers we just cut the header so installing the headers is absolutely very fast and just need to copy a few files into the destination rude and if we look at the directories we have here if I find all those that are in the lib streams we can see live streams and then use local include string.h and streams extra dot H so this is what you might expect be into the base system to set up missing dependent on stream CH and we'll use the ditto command to copy live stream route to sit and that it still again we can take farther proper is a lot of times when we do build the objects root has failed things may not tricking Exley that's one of my best practices that I didn't follow it was built it up the idea to clear out the object root and the symbol route thing from there with everything from there and dry again this time hopefully it'll it'll get a little further because add a file full of all it on the system by dependency back to the slides so again be careful always tax if your change on your base them it's also important not to overwrite the core foundation and work core foundation is an example of something that doesn't quite match up between Darwin and maca with a lot of extra functionality and Mac os10 that's not present on Darwin so if you were to replace it on your Mac os10 system things would fail to work in general the BFD commands and the BFC libraries are safe to replace so those those you don't need to worry about too much but xnu it's also generally safe to replace but since it is fictional any mistake will leave something on buddhist always have a bitten or CD or something you can boot again to reach your backup of the film I Iloka divers and families have those the same set of concerns basically it's the base of the system that decides the system will boot you real back up a run in kick things happened to these files if you have an extra partition that has a full system on it of course when you're booting you can use the option key to select which partition you want to boot if something goes wrong on your building partition use the option key to go back to pack of partition boot from that and then correct any problems I may have had generally for troubleshooting and I remember it's important to build this route things won't fail out but the difference to change owners might fail silently and so the build results you get won't be exactly what you were expecting as we saw a lot of times it's necessary to clear out the optimal route and even the deaf after each attempt to build the software their intermediate results in there sometimes the make files aren't as robust as they could be and they may further because tricked by a file that's in there so clearing those out you do a fresh stock and it usually makes things exceed if there's a header file missing you can use the install for phase 2 shortcut a build and of course if you have specific questions hesitate to ask a mailing list the Darwin development listal com is a good general starting point for Darwin questions and there are more specific lists for Colonel technologies or a series of Darwin and also at Darwin daughter Packers at a point org list where people who are involved the Darwin source code discuss this next I'll talk a little bit more advanced top building in a changed route a change is when you use the chain troop BSE command there's a good man page available on it that describes a little bit about what does and what essentially this does is it changes root directory flap to be a different sub directory on your disk and the advantage of doing this is it's men ssible to install heifers and install libraries compiler whatever need in a different environment than your host system so if something goes wrong in there it's less likely to affect the purchase that you're booting and it's also possible two or more easy targeting it and that's different than what you're running off for example if your thing on tends to be three or ten 34 because that's what's newest you want running but want things to work on and three and building up the change route with the 10 3 stuff will solve the problem of picking up library headers might have X isn't at that time because you're in a contained environment a couple things to note though it does change ipcc so it's still it's still important that you the same major version and although it's easy to do a change route to build you know tenth resources that's on a system that's actually 10 three four things inside the change route will communicate with the various demons on the system like look up d so if there's been any protocol change the change route doesn't doesn't reflect that and either might fail to work or get unexpected results so here i have an example script again you have to be root or to the root of the filesystem and when you change through to the filesystem some things will be missing like dev FS and a lot of a lot of poor needs that to compile so here i have an example of creating the directory in the route that we're going to change into mounting the dev FS filesystem on that dev directory mounting the file descriptor file system on top of that dev directory as well so that could see things like flash dev / null dev random the various file descriptors that are accessible from the shell and it's important to mount these file systems outside of the change route if you mount them inside of the change route and it might not be possible to unmount these file systems until you restart however if you if you mount them before changing into the root then it's possible to unmount them again silly so we change the route once this done and that will drop us into the default shell inside that root directory not to talk a bit about the Darwin build tools the darn build tools are scripts that I've developed recently that help to automate some of these tasks I've just just discussed so as you might imagine it'd be fairly yes if you had to type in all the text each time to set all the environment variables and pass all the same arguments to make and these scripts automate some of those processes the darn build tools are our two main components there's the darwin cross reference tool which is called darwin xref and what this can do is download a property list from the open darwin side or outside news property lists will be hopefully a bull soon there's an example one that that'll be that is available already with the tools for 10 3 4 and these property lists allow you to look up what the particular source work is for any project that's in Darwin that corresponds to say Mac OS 10 point three point four for example you can also list what projects that depends on so in order to build CC tools we saw that we need to first have the headers of live streams and that information is reflected in the Darwin xref tool and it's possible to ask that tool for a list of those types of dependencies and then another function that the darwin xref tool has is the ability to cross reference which files are installed on disk with which projects they came from so for example if we see that students that H is missing we can run a little weight on the Darwin xref tool and it will report back that lid streams is the project that that came from and again over time this information will be available for the darwin projects the darwin build script is a script that actually sets up the environment it uses the darwin xref tool accessibly to get the correct source versions it sets up the environment for building it also does a little bit of automatic fetching of the dependencies so if you don't have live streams already it'll go down the open darwin site and download it for example and it also helps automate change rooted building so it will create a directory it'll load up all the routes that are needed to change into their change the route perform the building in that isolated environment and the buildings poppy those files out of that isolated environment into a into a place that's ready for you to use so here's some example usages of the Darwin xref tool and again these tools are available at Darwin doors open Darwin org up top we have Darwin xref and we we load the index so we're taking build 7h 63 with mac OS 10 3 for the plist we downloaded from the website we load it into the into the dark school then we can do queries the first example is asking what version of the bourne shell was included in 10 3 4 and it says that was source version 29 next we can ask it to find filestream Shh and it notes that live streams project installs a file that's in user local include stream stream Shh and finally we ask it what are the runtime dependencies for the bourne shell and it knows that the board self requires live m libsystem CC tools and the increases library in order to run and there are other women sees which i don't have listed here the darwin build script as i mentioned will download sources from the darwin source web site so it automates that step you however you all have them on local system it'll use those or if you're modifying the sources it checks the local system first that's where you can put your modified version and have it build up the proper shell environment it saves roots and the symbols from a successful build in a in a directory hierarchy that's that's organized and ready to be used and it also installs any dependencies into a group before changing into it to perform the building so a couple examples here we can install the header files that are associated with the colonel by issuing the command darwin build dash headers xn you to do this example we just went out we could have done Darwin build cache headers live and another example of building the loop the standard c library would see in a change route and that's as simple as doing darwin build dash change route would see so now i'm going to demo those darwin build tools so we already have our bill brute directory I'll get rid of that echo yeah so we already have our dart or buildroot disconnect but we don't need any of this stuff that's already on it so I'm just going to wipe it away what I'm going to do now is install the Darwin build tools so these are available on that Darwin source open darwin org site and there's a read needs that that is on the site and also included in the guitar archive that explains how to set this up including creating the disk image and during the installation but I'm going to install this on to that build root image and here it creates some directories it creates sources objects symbols headers and routes and logs these are where the various results of your building will be stored so after resources are fetched from the open darwin site they'll be stored in the sources directory after the build has finished the symbols go into symbols directory the headers go in the headers directory the roots go in the roots directory and the log of the build is stored in the logs directory the first thing we need to do is look up the Darwin cross reference tool so I'll load that up with the sample property list that's included and you can see there are 313 projects listed in this property list so is the example I gave we can ask for what the version of bosch and it was Vash day 9 that's in the current systems build if you have other p lists that are of different build numbers it's possible to add extra arguments to the darwin cross reference tool and having felt one of those other builds that might be different from the system that you're already on so here we may want to build all of let's just do bash for example you can see it's fetching the stews and attempted to download them succeeded and it's going through and doing all the compiling it prints out some information about the local computer such as what version of GCC is an old what version of the Explorer is installed it also tells you what values that used to set up the shell environment variables but all the environment variables that were currently set on the system are what command it used to do the build and then it goes into a log here's configure and now it's actually going ahead and building some of these sources so I'll kill the building there for time but we can look in the logs and sure enough we have logs this is the bash project source version 29 attempt number one all of that output that I was just showing you has been saved into a log file so you can go back and review that at a later time now I'll give it a full of the change rigid building I it has the ability to download some of these pre-built routes from open darwin org but in the interest of time I already have them on the local disk and i'll just copy them over from there this is a collection of pre-built projects now the environment that's used to build is all stored in this Darwin build env file and again all these details are available in the documentation associated with the tools but since we'll be in a dark project let's say for fun that I want to enable the 386 variants of the architecture so here what I've done is I've changed around the variable so that not just powerpc is specified but also 386 is specified and I can do a Darwin build now by default Mac os10 does not ship a 386 tabled compiler but it is part of Darwin so to prove that that we're changing the route here i'm going to compile bash as we saw for 386 and Power PC in this change route environment so what it's doing right now is installing those routes which can be downloaded from open Darwin or as we see here they're already cached on the system it's copying all of those into the build root directory so first it is installed all see the libraries in binary said that the well maybe I can give a different example so as we can see here at least though the powerpc and I 386 architectures were specified it did compile those architectures in the change route environment apparently I still need to work a little bit more on specifying the dependencies in the property list file but if we look in the build where you can see it's a mini version of the of the respect that you might expect with directories like bin and espeon user applications developer etc and and also as I mentioned with mounting the the developer filesystem Deb FS is for the device file system sorry Deb if s is in that change route environment so it's the demo I have of the Darwin build tools I'll be going back to the slides and now talk about creating a bootable CD so it's possible to collect the Parwin projects install them onto a disk image and then burn the disk image and boot your ear from that for the sake of simplicity I'll be talked about using the HDI utilities to burn the CD which can only be done on Mac OS 10 there are steps for doing this on Darwin she'll be able to find on the open darwin site for a little bit more involved the first step is to get a CD image using the HDI to see and that shows up as an icon on the finder then you want to copy over the various projects that are needed to boot the computer a few finishing touches that need to be done which halts books include choosing a blessed of directory which which helps the open firmware on the computer boot from the CD as well as creating the text cash which computes all of the dependencies with the colonel and finally you burn the CD image so the steps creating a bootable CD is to use HDI you till the disk image in this example I'm creating a 650 megabyte disk image on an HFS partition I've given it a volume name of Darwin and this will will do the the normal process of creating a disk image and then we can attach it that's when the icon will show up on the desktop and you can change into the directory from terminal type etc it's important to set the ownership of this new volume 2 root wheel again if we're going to be copying a bunch of files into it you want the right default permissions so start off with root wheel and do all the copying is root so that all the ownership can be transferred you can use the ditto command to do the actual copying it's important to files project first that project is what has the directory hierarchy of a Mac os10 system it's what creates the user directory or the bin directory or the applications directory and so it's a good base to lay down and then all the other projects will start filling in those directories with their executables and with their libraries important to copy you that's the colonel boot X which is the boot loader with M is the standard math library libsystem CC tools which includes the dynamic linker start up the end curses library bash have a shell once you booted various file commands such as cprm the ones you're used to shell commands and the list on this will change goodly streets as things move around we'll try to keep some about it on the on the open darn sight but really for projects that for any release you absolutely need to have on the CD again there thur that probably need to have to have on your CD it's useful so the next step is to bless the CD image the command line tool called bless which hasn't man page so I suggest reading that and what that does is it sets a special bit on a dressing on the CD that lets open know that this is a CD that can be suited to the bootloader that should be used so in this example we will bless the folder that's the courses folder and that's where buddha i installed its its image we're also as a file label is actually then that appears on open full image that's pretty calculated when so a partition if you wake up an easy-to-read name when you hold down on your computer to decide white and to boot from step is the general mtext cash ashes basically pre computing colonel extension and their dependencies and how iraq to get into solid chunk can be loaded and in a single during boot the kext cap is what lets you generate wealth as an excellent man page so i suggest fitting that but for what we're doing is we're linking the mop thought the bootable CD the extensions direct CD and generating text file may report a few missing dependency observe some things of that the normal foot or two okay let's don't worry too much feel a large than perhaps something important is missing and generally what font is is you worse extensions and the folder is what using to boot the way you also want to create a startup script by d these darwin boot into a mode that looks for the login window it's a boob Mac os10 because that's what necklace it cook you can create the start of a simple it just drops to and you know what you want to do is have a little bit to commands and drop self and convince them you can you and I can that's what they used launched the install automatic Mac with the this is with binary competitiveness them that's been around and you on any of the systems that have been released so far to know if it does it does it doesn't different instructions online source so here what we can do is we can make a directory called min split which lets subscript puts an installer CD I'll at ccd which did go and execute that pile startup and we have the opportunity which will put us into this oh and that's really a bit to create full CD of doc you go and burn at onto the CP heating & bill so porn for me contacted the fit a manager I add that address puts entation in the odd make until what station about the Mac os10 file them it sings lamp or is an edge to it