1 File.........: overview.txt
2 Content......: Overview of how crosstool-NG works.
3 Copyrigth....: (C) 2007 Yann E. MORIN <yann.morin.1998@anciens.enib.fr>
4 License......: Creative Commons Attribution Share Alike (CC-by-sa), v2.5
14 Referring to crosstool-NG
15 Installing crosstool-NG
18 Preparing for packaging
21 Configuring crosstool-NG
22 Interesting config options
23 Re-building an existing toolchain
25 Stopping and restarting a build
26 Testing all toolchains at once
27 Overriding the number of // jobs
33 Seemingly-native toolchains
41 Adding a new version of a component
50 crosstool-NG aims at building toolchains. Toolchains are an essential component
51 in a software development project. It will compile, assemble and link the code
52 that is being developed. Some pieces of the toolchain will eventually end up
53 in the resulting binary/ies: static libraries are but an example.
55 So, a toolchain is a very sensitive piece of software, as any bug in one of the
56 components, or a poorly configured component, can lead to execution problems,
57 ranging from poor performance, to applications ending unexpectedly, to
58 mis-behaving software (which more than often is hard to detect), to hardware
59 damage, or even to human risks (which is more than regrettable).
61 Toolchains are made of different piece of software, each being quite complex
62 and requiring specially crafted options to build and work seamlessly. This
63 is usually not that easy, even in the not-so-trivial case of native toolchains.
64 The work reaches a higher degree of complexity when it comes to cross-
65 compilation, where it can become quite a nightmare...
67 Some cross-toolchains exist on the internet, and can be used for general
68 development, but they have a number of limitations:
69 - they can be general purpose, in that they are configured for the majority:
70 no optimisation for your specific target,
71 - they can be prepared for a specific target and thus are not easy to use,
72 nor optimised for, or even supporting your target,
73 - they often are using aging components (compiler, C library, etc...) not
74 supporting special features of your shiny new processor;
75 On the other side, these toolchain offer some advantages:
76 - they are ready to use and quite easy to install and setup,
77 - they are proven if used by a wide community.
79 But once you want to get all the juice out of your specific hardware, you will
80 want to build your own toolchain. This is where crosstool-NG comes into play.
82 There are also a number of tools that build toolchains for specific needs,
83 which are not really scalable. Examples are:
84 - buildroot (buildroot.uclibc.org) whose main purpose is to build root file
85 systems, hence the name. But once you have your toolchain with buildroot,
86 part of it is installed in the root-to-be, so if you want to build a whole
87 new root, you either have to save the existing one as a template and
88 restore it later, or restart again from scratch. This is not convenient,
89 - ptxdist (www.pengutronix.de/software/ptxdist), whose purpose is very
91 - other projects (openembedded.org for example), which are again used to
92 build root file systems.
94 crosstool-NG is really targeted at building toolchains, and only toolchains.
95 It is then up to you to use it the way you want.
103 crosstool was first 'conceived' by Dan Kegel, who offered it to the community
104 as a set of scripts, a repository of patches, and some pre-configured, general
105 purpose setup files to be used to configure crosstool. This is available at
106 http://www.kegel.com/crosstool, and the subversion repository is hosted on
107 google at http://code.google.com/p/crosstool/.
109 I once managed to add support for uClibc-based toolchains, but it did not make
110 into mainline, mostly because I didn't have time to port the patch forward to
111 the new versions, due in part to the big effort it was taking.
113 So I decided to clean up crosstool in the state it was, re-order the things
114 in place, add appropriate support for what I needed, that is uClibc support
115 and a menu-driven configuration, named the new implementation crosstool-NG,
116 (standing for crosstool Next Generation, as many other comunity projects do,
117 and as a wink at the TV series "Star Trek: The Next Generation" ;-) ) and
118 made it available to the community, in case it was of interest to any one.
121 _____________________________
123 Referring to crosstool-NG /
124 __________________________/
127 The long name of the project is crosstool-NG:
128 * no leading uppercase (except as first word in a sentence)
129 * crosstool and NG separated with a hyphen (dash)
132 Crosstool-NG can also be referred to by its short name CT-NG:
134 * CT and NG separated with a hyphen (dash)
136 The long name is preferred over the short name, except in mail subjects, where
137 the short name is a better fit.
139 When referring to a specific version of crosstool-NG, append the version number
142 - the long name, a space, and the version string
144 - the long name in lowercase, a hyphen (dash), and the version string
145 - this is used to name the release tarballs
146 * crosstool-ng-X.Y.Z+hg_id
147 - the long name in lowercase, a hyphen, the version string, and the Hg id
148 (as returned by: ct-ng version)
149 - this is used to differentiate between releases and snapshots
151 The frontend to crosstool-NG is the command ct-ng:
153 * ct and ng separated by a hyphen (dash)
156 ___________________________
158 Installing crosstool-NG /
159 ________________________/
161 There are two ways you can use crosstool-NG:
162 - build and install it, then get rid of the sources like you'd do for most
164 - or only build it and run from the source directory.
166 The former should be used if you got crosstool-NG from a packaged tarball, see
167 "Install method", below, while the latter is most useful for developpers that
168 use a clone of the repository, and want to submit patches, see "The Hacker's
174 If you go for the install, then you just follow the classical, but yet easy
176 ./configure --prefix=/some/place
179 export PATH="${PATH}:/some/place/bin"
181 You can then get rid of crosstool-NG source. Next create a directory to serve
182 as a working place, cd in there and run:
185 See below for complete usage.
190 If you go the hacker's way, then the usage is a bit different, although very
195 Now, *do not* remove crosstool-NG sources. They are needed to run crosstool-NG!
196 Stay in the directory holding the sources, and run:
199 See below for complete usage.
201 Now, provided you used a clone of the repository, you can send me your changes.
202 See the section titled CONTRIBUTING, below, for how to submit changees.
204 Preparing for packaging |
205 ------------------------+
207 If you plan on packaging crosstool-NG, you surely don't want to install it
208 in your root file system. The install procedure of crosstool-NG honors the
211 ./configure --prefix=/usr
213 make DESTDIR=/packaging/place install
218 crosstool-NG comes with a shell script fragment that defines bash-compatible
219 completion. That shell fragment is currently not installed automatically, but
222 To install the shell script fragment, you have two options:
223 - install system-wide, most probably by copying ct-ng.comp into
224 /etc/bash_completion.d/
225 - install for a single user, by copying ct-ng.comp into ${HOME}/ and
226 sourcing this file from your ${HOME}/.bashrc
231 Some people contibuted code that couldn't get merged for various reasons. This
232 code is available as lzma-compressed patches, in the contrib/ sub-directory.
233 These patches are to be applied to the source of crosstool-NG, prior to
234 installing, using something like the following:
235 lzcat contrib/foobar.patch.lzma |patch -p1
237 There is no guarantee that a particuliar contribution applies to the current
238 version of crosstool-ng, or that it will work at all. Use contributions at
242 ____________________________
244 Configuring crosstool-NG /
245 _________________________/
247 crosstool-NG is configured with a configurator presenting a menu-stuctured set
248 of options. These options let you specify the way you want your toolchain
249 built, where you want it installed, what architecture and specific processor it
250 will support, the version of the components you want to use, etc... The
251 value for those options are then stored in a configuration file.
253 The configurator works the same way you configure your Linux kernel. It is
254 assumed you now how to handle this.
256 To enter the menu, type:
259 Almost every config item has a help entry. Read them carefully.
261 String and number options can refer to environment variables. In such a case,
262 you must use the shell syntax: ${VAR}. You shall neither single- nor double-
263 quote the string/number options.
265 There are three environment variables that are computed by crosstool-NG, and
269 It represents the target tuple you are building for. You can use it for
270 example in the installation/prefix directory, such as:
271 /opt/x-tools/${CT_TARGET}
274 The top directory where crosstool-NG is running. You shouldn't need it in
275 most cases. There is one case where you may need it: if you have local
276 patches and you store them in your running directory, you can refer to them
277 by using CT_TOP_DIR, such as:
278 ${CT_TOP_DIR}/patches.myproject
281 The version of crosstool-NG you are using. Not much use for you, but it's
282 there if you need it.
284 Interesting config options |
285 ---------------------------+
287 CT_LOCAL_TARBALLS_DIR:
288 If you already have some tarballs in a direcotry, enter it here. That will
289 speed up the retrieving phase, where crosstool-NG would otherwise download
293 This is where the toolchain will be installed in (and for now, where it
294 will run from). Common use is to add the target tuple in the directory
295 path, such as (see above):
296 /opt/x-tools/${CT_TARGET}
299 An identifier for your toolchain, will take place in the vendor part of the
300 target tuple. It shall *not* contain spaces or dashes. Usually, keep it
301 to a one-word string, or use underscores to separate words if you need.
302 Avoid dots, commas, and special characters.
305 An alias for the toolchian. It will be used as a prefix to the toolchain
306 tools. For example, you will have ${CT_TARGET_ALIAS}-gcc
308 Also, if you think you don't see enough versions, you can try to enable one of
312 Show obsolete versions or tools. Most of the time, you don't want to base
313 your toolchain on too old a version (of gcc, for example). But at times, it
314 can come handy to use such an old version for regression tests. Those old
315 versions are hidden behind CT_OBSOLETE. Those versions (or features) are so
316 marked because maintaining support for those in crosstool-NG would be too
317 costly, time-wise, and time is dear.
320 Show experimental versions or tools. Again, you might not want to base your
321 toolchain on too recent tools (eg. gcc) for production. But if you need a
322 feature present only in a recent version, or a new tool, you can find them
323 hidden behind CT_EXPERIMENTAL. Those versions (or features) did not (yet)
324 receive thorough testing in crosstool-NG, and/or are not mature enough to
327 Re-building an existing toolchain |
328 ----------------------------------+
330 If you have an existing toolchain, you can re-use the options used to build it
331 to create a new toolchain. That needs a very little bit of effort on your side
332 but is quite easy. The options to build a toolchain are saved with the
333 toolchain, and you can retrieve this configuration by running:
334 ${CT_TARGET}-ct-ng.config
336 An alternate method is to extract the configuration from a build.log file.
337 This will be necessary if your toolchain was build with crosstool-NG prior
338 to 1.4.0, but can be used with build.log files from any version:
339 ct-ng extractconfig <build.log >.config
341 Or, if your build.log file is compressed (most probably!):
342 bzcat build.log.bz2 |ct-ng extractconfig >.config
344 The above commands will dump the configuration to stdout, so to rebuild a
345 toolchain with this configuration, just redirect the output to the
347 ${CT_TARGET}-ct-ng.config >.config
350 Then, you can review and change the configuration by running:
354 ________________________
356 Running crosstool-NG /
357 _____________________/
359 To build the toolchain, simply type:
362 This will use the above configuration to retrieve, extract and patch the
363 components, build, install and eventually test your newly built toolchain.
365 You are then free to add the toolchain /bin directory in your PATH to use
368 In any case, you can get some terse help. Just type:
373 Stopping and restarting a build |
374 --------------------------------+
376 If you want to stop the build after a step you are debugging, you can pass the
377 variable STOP to make:
378 ct-ng build STOP=some_step
380 Conversely, if you want to restart a build at a specific step you are
381 debugging, you can pass the RESTART variable to make:
382 ct-ng build RESTART=some_step
384 Alternatively, you can call make with the name of a step to just do that step:
387 ct-ng build RESTART=libc_headers STOP=libc_headers
389 The shortcuts +step_name and step_name+ allow to respectively stop or restart
391 ct-ng +libc_headers and: ct-ng libc_headers+
393 ct-ng build STOP=libc_headers and: ct-ng build RESTART=libc_headers
395 To obtain the list of acceptable steps, please call:
398 Note that in order to restart a build, you'll have to say 'Y' to the config
399 option CT_DEBUG_CT_SAVE_STEPS, and that the previous build effectively went
402 Building all toolchains at once |
403 --------------------------------+
405 You can build all samples; simply call:
408 Overriding the number of // jobs |
409 ---------------------------------+
411 If you want to override the number of jobs to run in // (the -j option to
412 make), you can either re-enter the menuconfig, or simply add it on the command
416 which tells crosstool-NG to override the number of // jobs to 4.
418 You can see the actions that support overriding the number of // jobs in
419 the help menu. Those are the ones with [.#] after them (eg. build[.#] or
420 build-all[.#], and so on...).
425 The crosstool-NG script 'ct-ng' is a Makefile-script. It does *not* execute
426 in parallel (there is not much to gain). When speaking of // jobs, we are
427 refering to the number of // jobs when making the *components*. That is, we
428 speak of the number of // jobs used to build gcc, glibc, and so on...
433 Starting with gcc-4.3 come two new dependencies: GMP and MPFR. With gcc-4.4,
434 come three new ones: GMP, PPL and CLooG/ppl. These are libraries that enable
435 advanced features to gcc. Additionally, some of the libraries can be used by
436 binutils and gdb. Unfortunately, not all systems on which crosstool-NG runs
437 have all of those libraries. And for those that do, the versions of those
438 libraries may be older than the version required by gcc.
440 This is why crosstool-NG builds its own set of libraries as part of the
443 The libraries are built as shared libraries, because building them as static
444 libraries has some short-comings. This poses no problem at build time, as
445 crosstool-NG correctly points gcc (and binutils and gdb) to the correct
446 place where our own version of the libraries are installed. But it poses
447 a problem when gcc et al. are run: the place where the libraries are is most
448 probably not known to the host dynamic linker. Still worse, if the host system
449 has its own versions, then ld.so would load the wrong library!
451 So we have to force the dynamic linker to load the correct version. We do this
452 by using the LD_LIBRARY_PATH variable, that informs the dynamic linker where
453 to look for shared libraries prior to searching its standard places. But we
454 can't impose that burden on all the system (because it'd be a nightmare to
455 configure, and because two toolchains on the same system may use different
456 versions of the libraries); so we have to do it on a per-toolchain basis.
458 So we rename all binaries of the toolchain (by adding a dot '.' as their first
459 character), and add a small program, the so-called "tools wrapper", that
460 correctly sets LD_LIBRARY_PATH prior to running the real tool.
462 First, the wrapper was written as a POSIX-compliant shell script. That shell
463 script is very simple, if not trivial, and works great. The only drawback is
464 that it does not work on host systems that lack a shell, for example the
465 MingW32 environment. To solve the issue, the wrapper has been re-written in C,
466 and compiled at build time. This C wrapper is much more complex than the shell
467 script, and although it sems to be working, it's been only lightly tested.
468 Some of the expected short-comings with this C wrapper are;
469 - multi-byte file names may not be handled correctly
470 - it's really big for what it does
472 So, the default wrapper installed with your toolchain is the shell script.
473 If you know that your system is missing a shell, then you shall use the C
474 wrapper (and report back whether it works, or does not work, for you).
477 _______________________
479 Using the toolchain /
480 ____________________/
482 Using the toolchain is as simple as adding the toolchain's bin directory in
484 export PATH="${PATH}:/your/toolchain/path/bin"
486 and then using the target tuple to tell the build systems to use your
488 ./configure --target=your-target-tuple
490 make CC=your-target-tuple-gcc
492 make CROSS_COMPILE=your-target-tuple-
495 It is strongly advised not to use the toolchain sys-root directory as an
496 install directory for your programs/packages. If you do so, you will not be
497 able to use your toolchain for another project. It is even strongly advised
498 that your toolchain is chmod-ed to read-only once successfully build, so that
499 you don't go polluting your toolchain with your programs/packages' files.
501 Thus, when you build a program/package, install it in a separate directory,
502 eg. /your/root. This directory is the /image/ of what would be in the root file
503 system of your target, and will contain all that your programs/packages have
506 The 'populate' script |
507 ----------------------+
509 When your root directory is ready, it is still missing some important bits: the
510 toolchain's libraries. To populate your root directory with those libs, just
512 your-target-tuple-populate -s /your/root -d /your/root-populated
514 This will copy /your/root into /your/root-populated, and put the needed and only
515 the needed libraries there. Thus you don't polute /your/root with any cruft that
516 would no longer be needed should you have to remove stuff. /your/root always
517 contains only those things you install in it.
519 You can then use /your/root-populated to build up your file system image, a
520 tarball, or to NFS-mount it from your target, or whatever you need.
522 The populate script accepts the following options:
525 Use 'src_dir' as the un-populated root directory.
528 Put the populated root directory in 'dst_dir'.
531 Always add specified libraries.
534 Always add libraries listed in 'file'.
537 Remove 'dst_dir' if it previously existed; continue even if any library
538 specified with -l or -L is missing.
541 Be verbose, and tell what's going on (you can see exactly where libs are
547 See 'your-target-tuple-populate -h' for more information on the options.
549 Here is how populate works:
551 1) performs some sanity checks:
552 - src_dir and dst_dir are specified
554 - unless forced, dst_dir does not exist
557 2) copy src_dir to dst_dir
559 3) add forced libraries to dst_dir
560 - build the list from -l and -L options
561 - get forced libraries from the sysroot (see below for heuristics)
562 - abort on the first missing library, unless -f is specified
564 4) add all missing libraries to dst_dir
565 - scan dst_dir for every ELF files that are 'executable' or
567 - list the "NEEDED Shared library" fields
568 - check if the library is already in dst_dir/lib or dst_dir/usr/lib
569 - if not, get the library from the sysroot
570 - if it's in sysroot/lib, copy it to dst_dir/lib
571 - if it's in sysroot/usr/lib, copy it to dst_dir/usr/lib
572 - in both cases, use the SONAME of the library to create the file
574 - if it was not found in the sysroot, this is an error.
582 There are four kinds of toolchains you could encounter.
584 First off, you must understand the following: when it comes to compilers there
585 are up to four machines involved:
586 1) the machine configuring the toolchain components: the config machine
587 2) the machine building the toolchain components: the build machine
588 3) the machine running the toolchain: the host machine
589 4) the machine the toolchain is generating code for: the target machine
591 We can most of the time assume that the config machine and the build machine
592 are the same. Most of the time, this will be true. The only time it isn't
593 is if you're using distributed compilation (such as distcc). Let's forget
594 this for the sake of simplicity.
596 So we're left with three machines:
601 Any toolchain will involve those three machines. You can be as pretty sure of
602 this as "2 and 2 are 4". Here is how they come into play:
604 1) build == host == target
605 This is a plain native toolchain, targetting the exact same machine as the
606 one it is built on, and running again on this exact same machine. You have
607 to build such a toolchain when you want to use an updated component, such
608 as a newer gcc for example.
609 crosstool-NG calls it "native".
611 2) build == host != target
612 This is a classic cross-toolchain, which is expected to be run on the same
613 machine it is compiled on, and generate code to run on a second machine,
615 crosstool-NG calls it "cross".
617 3) build != host == target
618 Such a toolchain is also a native toolchain, as it targets the same machine
619 as it runs on. But it is build on another machine. You want such a
620 toolchain when porting to a new architecture, or if the build machine is
621 much faster than the host machine.
622 crosstool-NG calls it "cross-native".
624 4) build != host != target
625 This one is called a canadian-toolchain (*), and is tricky. The three
626 machines in play are different. You might want such a toolchain if you
627 have a fast build machine, but the users will use it on another machine,
628 and will produce code to run on a third machine.
629 crosstool-NG calls it "canadian".
631 crosstool-NG can build all these kinds of toolchains (or is aiming at it,
634 (*) The term Canadian Cross came about because at the time that these issues
635 were all being hashed out, Canada had three national political parties.
636 http://en.wikipedia.org/wiki/Cross_compiler
644 Sending a bug report |
645 ---------------------+
647 If you need to send a bug report, please send a mail with subject
648 prefixed with "[CT_NG]" with to following destinations:
649 TO: yann.morin.1998 (at) anciens.enib.fr
650 CC: crossgcc (at) sourceware.org
655 If you want to enhance crosstool-NG, there's a to-do list in the TODO file.
657 Patches should come with the appropriate SoB line. A SoB line is typically
659 Signed-off-by: John DOE <john.doe@somewhere.net>
661 The SoB line is clearly described in Documentation/SubmittingPatches , section
662 12, of your favourite Linux kernel source tree.
664 Then you'll need to correctly configure Mercurial. There are two extensions
665 that you may find usefull:
666 - mq : http://mercurial.selenic.com/wiki/MqExtension
667 - patchbomb : http://mercurial.selenic.com/wiki/PatchbombExtension
669 Commit messages should look like (without leading pipes):
670 |component: short, one-line description
672 |optional longer description
673 |on multiple lines if needed
675 Here is an example commit message (see revision a53a5e1d61db):
676 |comp-libs/cloog: fix building
678 |For CLooG/PPL 0.15.3, the directory name was simply cloog-ppl.
679 |For any later versions, the directory name does have the version, such as
682 Here's a typical hacking session:
683 hg clone http://ymorin.is-a-geek.org/hg/crosstool-ng crosstool-ng
686 hg qnew -D -U -e my_first_patch
687 *edit patch description*
688 *hack* *hack* *check* *fails* *hack* *hack* *check* *works*
690 *edit patch description, serving as commit message*
691 hg qnew -D -U -e my_second_patch
692 *edit patch description*
693 *hack* *hack* *check* *fails* *hack* *hack* *check* *works*
695 *edit patch description, serving as commit message*
696 hg email --outgoing --intro \
697 --from '"Your Full NAME" <your.email (at) your.domain>' \
698 --to '"Yann E. MORIN" <yann.morin.1998 (at) anciens.enib.fr>' \
699 --cc 'crossgcc (at) sourceware.org'
700 *edit introductory message*
702 *re-send if no answer for a few days*
704 Note: replace '(at)' above with a plain '@'.
712 Internally, crosstool-NG is script-based. To ease usage, the frontend is
718 The entry point to crosstool-NG is the Makefile script "ct-ng". Calling this
719 script with an action will act exactly as if the Makefile was in the current
720 working directory and make was called with the action as rule. Thus:
723 is equivalent to having the Makefile in CWD, and calling:
726 Having ct-ng as it is avoids copying the Makefile everywhere, and acts as a
729 ct-ng loads sub- Makefiles from the library directory $(CT_LIB_DIR), as set up
730 at configuration time with ./configure.
732 ct-ng also searches for config files, sub-tools, samples, scripts and patches in
733 that library directory.
735 Because of a stupid make behavior/bug I was unable to track down, implicit make
736 rules are disabled: installing with --local would triger those rules, and mconf
742 The kconfig language is a hacked version, vampirised from the Linux kernel
743 (http://www.kernel.org/), and (heavily) adapted to my needs.
745 The list of the most notable changes (at least the ones I remember) follows:
746 - the CONFIG_ prefix has been replaced with CT_
747 - a leading | in prompts is skipped, and subsequent leading spaces are not
749 - otherwise leading spaces are silently trimmed
751 The kconfig parsers (conf and mconf) are not installed pre-built, but as
752 source files. Thus you can have the directory where crosstool-NG is installed,
753 exported (via NFS or whatever) and have clients with different architectures
754 use the same crosstool-NG installation, and most notably, the same set of
757 Architecture-specific |
758 ----------------------+
760 Note: this chapter is not really well written, and might thus be a little bit
761 complex to understand. To get a better grasp of what an architecture is, the
762 reader is kindly encouraged to look at the "arch/" sub-directory, and to the
763 existing architectures to see how things are laid out.
765 An architecture is defined by:
767 - a human-readable name, in lower case letters, with numbers as appropriate.
768 The underscore is allowed; space and special characters are not.
770 - a file in "config/arch/", named after the architecture's name, and suffixed
772 Eg.: config/arch/arm.in
773 - a file in "scripts/build/arch/", named after the architecture's name, and
775 Eg.: scripts/build/arch/arm.sh
777 The architecture's ".in" file API:
778 > the config option "ARCH_%arch%" (where %arch% is to be replaced with the
779 actual architecture name).
780 That config option must have *neither* a type, *nor* a prompt! Also, it can
781 *not* depend on any other config option (EXPERIMENTAL is managed as above).
785 defines a (terse) help entry for this architecture:
789 The ARM architecture.
791 selects adequate associated config options.
792 Note: 64-bit architectures *shall* select ARCH_64
795 select ARCH_SUPPORTS_BOTH_ENDIAN
796 select ARCH_DEFAULT_LE
798 The ARM architecture.
803 The x86_64 architecture.
805 > other target-specific options, at your discretion. Note however that to
806 avoid name-clashing, such options shall be prefixed with "ARCH_%arch%",
807 where %arch% is again replaced by the actual architecture name.
808 (Note: due to historical reasons, and lack of time to clean up the code,
809 I may have left some config options that do not completely conform to
810 this, as the architecture name was written all upper case. However, the
811 prefix is unique among architectures, and does not cause harm).
813 The architecture's ".sh" file API:
814 > the function "CT_DoArchTupleValues"
817 - all variables from the ".config" file,
818 - the two variables "target_endian_eb" and "target_endian_el" which are
819 the endianness suffixes
820 + return value: 0 upon success, !0 upon failure
823 - the environment variable CT_TARGET_ARCH
825 the architecture part of the target tuple.
826 Eg.: "armeb" for big endian ARM
830 - the environment variable CT_TARGET_SYS
832 the sytem part of the target tuple.
833 Eg.: "gnu" for glibc on most architectures
834 "gnueabi" for glibc on an ARM EABI
836 - for glibc-based toolchain: "gnu"
837 - for uClibc-based toolchain: "uclibc"
840 - the environment variables to configure the cross-gcc (defaults)
841 - CT_ARCH_WITH_ARCH : the gcc ./configure switch to select architecture level ( "--with-arch=${CT_ARCH_ARCH}" )
842 - CT_ARCH_WITH_ABI : the gcc ./configure switch to select ABI level ( "--with-abi=${CT_ARCH_ABI}" )
843 - CT_ARCH_WITH_CPU : the gcc ./configure switch to select CPU instruction set ( "--with-cpu=${CT_ARCH_CPU}" )
844 - CT_ARCH_WITH_TUNE : the gcc ./configure switch to select scheduling ( "--with-tune=${CT_ARCH_TUNE}" )
845 - CT_ARCH_WITH_FPU : the gcc ./configure switch to select FPU type ( "--with-fpu=${CT_ARCH_FPU}" )
846 - CT_ARCH_WITH_FLOAT : the gcc ./configure switch to select floating point arithmetics ( "--with-float=soft" or /empty/ )
849 - the environment variables to pass to the cross-gcc to build target binaries (defaults)
850 - CT_ARCH_ARCH_CFLAG : the gcc switch to select architecture level ( "-march=${CT_ARCH_ARCH}" )
851 - CT_ARCH_ABI_CFLAG : the gcc switch to select ABI level ( "-mabi=${CT_ARCH_ABI}" )
852 - CT_ARCH_CPU_CFLAG : the gcc switch to select CPU instruction set ( "-mcpu=${CT_ARCH_CPU}" )
853 - CT_ARCH_TUNE_CFLAG : the gcc switch to select scheduling ( "-mtune=${CT_ARCH_TUNE}" )
854 - CT_ARCH_FPU_CFLAG : the gcc switch to select FPU type ( "-mfpu=${CT_ARCH_FPU}" )
855 - CT_ARCH_FLOAT_CFLAG : the gcc switch to choose floating point arithmetics ( "-msoft-float" or /empty/ )
856 - CT_ARCH_ENDIAN_CFLAG : the gcc switch to choose big or little endian ( "-mbig-endian" or "-mlittle-endian" )
861 - the environement variables to configure the core and final compiler, specific to this architecture:
862 - CT_ARCH_CC_CORE_EXTRA_CONFIG : additional, architecture specific core gcc ./configure flags
863 - CT_ARCH_CC_EXTRA_CONFIG : additional, architecture specific final gcc ./configure flags
868 - the architecture-specific CFLAGS and LDFLAGS:
869 - CT_ARCH_TARGET_CLFAGS
870 - CT_ARCH_TARGET_LDFLAGS
874 You can have a look at "config/arch/arm.in" and "scripts/build/arch/arm.sh" for
875 a quite complete example of what an actual architecture description looks like.
880 A kernel is defined by:
882 - a human-readable name, in lower case letters, with numbers as appropriate.
883 The underscore is allowed; space and special characters are not (although
884 they are internally replaced with underscores.
885 Eg.: linux, bare-metal
886 - a file in "config/kernel/", named after the kernel name, and suffixed with
888 Eg.: config/kernel/linux.in, config/kernel/bare-metal.in
889 - a file in "scripts/build/kernel/", named after the kernel name, and suffixed
891 Eg.: scripts/build/kernel/linux.sh, scripts/build/kernel/bare-metal.sh
893 The kernel's ".in" file must contain:
894 > an optional lines containing exactly "# EXPERIMENTAL", starting on the
895 first column, and without any following space or other character.
896 If this line is present, then this kernel is considered EXPERIMENTAL,
897 and correct dependency on EXPERIMENTAL will be set.
899 > the config option "KERNEL_%kernel_name%" (where %kernel_name% is to be
900 replaced with the actual kernel name, with all special characters and
901 spaces replaced by underscores).
902 That config option must have *neither* a type, *nor* a prompt! Also, it can
903 *not* depends on EXPERIMENTAL.
904 Eg.: KERNEL_linux, KERNEL_bare_metal
906 defines a (terse) help entry for this kernel.
908 config KERNEL_bare_metal
910 Build a compiler for use without any kernel.
912 selects adequate associated config options.
914 config KERNEL_bare_metal
917 Build a compiler for use without any kernel.
919 > other kernel specific options, at your discretion. Note however that, to
920 avoid name-clashing, such options should be prefixed with
921 "KERNEL_%kernel_name%", where %kernel_name% is again tp be replaced with
922 the actual kernel name.
923 (Note: due to historical reasons, and lack of time to clean up the code,
924 I may have left some config options that do not completely conform to
925 this, as the kernel name was written all upper case. However, the prefix
926 is unique among kernels, and does not cause harm).
928 The kernel's ".sh" file API:
929 > is a bash script fragment
931 > defines the function CT_DoKernelTupleValues
932 + see the architecture's CT_DoArchTupleValues, except for:
933 + set the environment variable CT_TARGET_KERNEL, the kernel part of the
935 + return value: ignored
937 > defines the function "do_kernel_get":
940 - all variables from the ".config" file.
941 + return value: 0 for success, !0 for failure.
942 + behavior: download the kernel's sources, and store the tarball into
943 "${CT_TARBALLS_DIR}". To this end, a functions is available, that
944 abstracts downloading tarballs:
945 - CT_DoGet <tarball_base_name> <URL1 [URL...]>
946 Eg.: CT_DoGet linux-2.6.26.5 ftp://ftp.kernel.org/pub/linux/kernel/v2.6
947 Note: retrieving sources from svn, cvs, git and the likes is not supported
948 by CT_DoGet. You'll have to do this by hand, as it is done for eglibc in
949 "scripts/build/libc/eglibc.sh"
951 > defines the function "do_kernel_extract":
954 - all variables from the ".config" file,
955 + return value: 0 for success, !0 for failure.
956 + behavior: extract the kernel's tarball into "${CT_SRC_DIR}", and apply
957 required patches. To this end, a function is available, that abstracts
959 - CT_ExtractAndPatch <tarball_base_name>
960 Eg.: CT_ExtractAndPatch linux-2.6.26.5
962 > defines the function "do_kernel_headers":
965 - all variables from the ".config" file,
966 + return value: 0 for success, !0 for failure.
967 + behavior: install the kernel headers (if any) in "${CT_SYSROOT_DIR}/usr/include"
969 > defines any kernel-specific helper functions
970 These functions, if any, must be prefixed with "do_kernel_%CT_KERNEL%_",
971 where '%CT_KERNEL%' is to be replaced with the actual kernel name, to avoid
974 You can have a look at "config/kernel/linux.in" and "scripts/build/kernel/linux.sh"
975 as an example of what a complex kernel description looks like.
977 Adding a new version of a component |
978 ------------------------------------+
980 When a new component, such as the Linux kernel, gcc or any other is released,
981 adding the new version to crosstool-NG is quite easy. There is a script that
982 will do all that for you:
983 scripts/addToolVersion.sh
985 Run it with no option to get some help.
990 To Be Written later...