yann@2076: File.........: 1 - Introduction.txt antony@2563: Copyright....: (C) 2010 Yann E. MORIN yann@2076: License......: Creative Commons Attribution Share Alike (CC-by-sa), v2.5 yann@2076: yann@2076: yann@2076: Introduction / yann@2076: _____________/ yann@2076: yann@2076: yann@2076: crosstool-NG aims at building toolchains. Toolchains are an essential component yann@2076: in a software development project. It will compile, assemble and link the code yann@2076: that is being developed. Some pieces of the toolchain will eventually end up yann@2076: in the resulting binary/ies: static libraries are but an example. yann@2076: yann@2076: So, a toolchain is a very sensitive piece of software, as any bug in one of the yann@2076: components, or a poorly configured component, can lead to execution problems, yann@2076: ranging from poor performance, to applications ending unexpectedly, to yann@2076: mis-behaving software (which more than often is hard to detect), to hardware yann@2076: damage, or even to human risks (which is more than regrettable). yann@2076: yann@2076: Toolchains are made of different piece of software, each being quite complex yann@2076: and requiring specially crafted options to build and work seamlessly. This yann@2076: is usually not that easy, even in the not-so-trivial case of native toolchains. yann@2076: The work reaches a higher degree of complexity when it comes to cross- yann@2076: compilation, where it can become quite a nightmare... yann@2076: yann@2076: Some cross-toolchains exist on the internet, and can be used for general yann@2076: development, but they have a number of limitations: yann@2076: - they can be general purpose, in that they are configured for the majority: yann@2076: no optimisation for your specific target, yann@2076: - they can be prepared for a specific target and thus are not easy to use, yann@2076: nor optimised for, or even supporting your target, yann@2076: - they often are using aging components (compiler, C library, etc...) not yann@2076: supporting special features of your shiny new processor; yann@2076: On the other side, these toolchain offer some advantages: yann@2076: - they are ready to use and quite easy to install and setup, yann@2076: - they are proven if used by a wide community. yann@2076: yann@2076: But once you want to get all the juice out of your specific hardware, you will yann@2076: want to build your own toolchain. This is where crosstool-NG comes into play. yann@2076: yann@2076: There are also a number of tools that build toolchains for specific needs, yann@2076: which are not really scalable. Examples are: yann@2076: - buildroot (buildroot.uclibc.org) whose main purpose is to build root file yann@2076: systems, hence the name. But once you have your toolchain with buildroot, yann@2076: part of it is installed in the root-to-be, so if you want to build a whole yann@2076: new root, you either have to save the existing one as a template and yann@2076: restore it later, or restart again from scratch. This is not convenient, yann@2076: - ptxdist (www.pengutronix.de/software/ptxdist), whose purpose is very yann@2076: similar to buildroot, yann@2076: - other projects (openembedded.org for example), which are again used to yann@2076: build root file systems. yann@2076: yann@2076: crosstool-NG is really targeted at building toolchains, and only toolchains. yann@2076: It is then up to you to use it the way you want. yann@2076: yann@2076: yann@2076: History | yann@2076: --------+ yann@2076: yann@2076: crosstool was first 'conceived' by Dan Kegel, who offered it to the community yann@2076: as a set of scripts, a repository of patches, and some pre-configured, general yann@2076: purpose setup files to be used to configure crosstool. This is available at yann@2076: http://www.kegel.com/crosstool, and the subversion repository is hosted on yann@2076: google at http://code.google.com/p/crosstool/. yann@2076: yann@2076: I once managed to add support for uClibc-based toolchains, but it did not make yann@2076: into mainline, mostly because I didn't have time to port the patch forward to yann@2076: the new versions, due in part to the big effort it was taking. yann@2076: yann@2076: So I decided to clean up crosstool in the state it was, re-order the things yann@2076: in place, add appropriate support for what I needed, that is uClibc support yann@2076: and a menu-driven configuration, named the new implementation crosstool-NG, antony@2564: (standing for crosstool Next Generation, as many other community projects do, yann@2076: and as a wink at the TV series "Star Trek: The Next Generation" ;-) ) and yann@2076: made it available to the community, in case it was of interest to any one. yann@2076: yann@2076: yann@2076: Referring to crosstool-NG | yann@2076: --------------------------+ yann@2076: yann@2076: The long name of the project is crosstool-NG: yann@2076: * no leading uppercase (except as first word in a sentence) yann@2076: * crosstool and NG separated with a hyphen (dash) yann@2076: * NG in uppercase yann@2076: yann@2076: Crosstool-NG can also be referred to by its short name CT-NG: yann@2076: * all in uppercase yann@2076: * CT and NG separated with a hyphen (dash) yann@2076: yann@2076: The long name is preferred over the short name, except in mail subjects, where yann@2076: the short name is a better fit. yann@2076: yann@2076: When referring to a specific version of crosstool-NG, append the version number yann@2076: either as: yann@2076: * crosstool-NG X.Y.Z yann@2076: - the long name, a space, and the version string yann@2076: * crosstool-ng-X.Y.Z yann@2076: - the long name in lowercase, a hyphen (dash), and the version string yann@2076: - this is used to name the release tarballs yann@2076: * crosstool-ng-X.Y.Z+hg_id yann@2076: - the long name in lowercase, a hyphen, the version string, and the Hg id yann@2076: (as returned by: ct-ng version) yann@2076: - this is used to differentiate between releases and snapshots yann@2076: yann@2076: The frontend to crosstool-NG is the command ct-ng: yann@2076: * all in lowercase yann@2076: * ct and ng separated by a hyphen (dash)