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
24 Using as a backend for a build-system
26 Stopping and restarting a build
27 Testing all toolchains at once
28 Overriding the number of // jobs
34 Seemingly-native toolchains
42 Adding a new version of a component
51 crosstool-NG aims at building toolchains. Toolchains are an essential component
52 in a software development project. It will compile, assemble and link the code
53 that is being developed. Some pieces of the toolchain will eventually end up
54 in the resulting binary/ies: static libraries are but an example.
56 So, a toolchain is a very sensitive piece of software, as any bug in one of the
57 components, or a poorly configured component, can lead to execution problems,
58 ranging from poor performance, to applications ending unexpectedly, to
59 mis-behaving software (which more than often is hard to detect), to hardware
60 damage, or even to human risks (which is more than regrettable).
62 Toolchains are made of different piece of software, each being quite complex
63 and requiring specially crafted options to build and work seamlessly. This
64 is usually not that easy, even in the not-so-trivial case of native toolchains.
65 The work reaches a higher degree of complexity when it comes to cross-
66 compilation, where it can become quite a nightmare...
68 Some cross-toolchains exist on the internet, and can be used for general
69 development, but they have a number of limitations:
70 - they can be general purpose, in that they are configured for the majority:
71 no optimisation for your specific target,
72 - they can be prepared for a specific target and thus are not easy to use,
73 nor optimised for, or even supporting your target,
74 - they often are using aging components (compiler, C library, etc...) not
75 supporting special features of your shiny new processor;
76 On the other side, these toolchain offer some advantages:
77 - they are ready to use and quite easy to install and setup,
78 - they are proven if used by a wide community.
80 But once you want to get all the juice out of your specific hardware, you will
81 want to build your own toolchain. This is where crosstool-NG comes into play.
83 There are also a number of tools that build toolchains for specific needs,
84 which are not really scalable. Examples are:
85 - buildroot (buildroot.uclibc.org) whose main purpose is to build root file
86 systems, hence the name. But once you have your toolchain with buildroot,
87 part of it is installed in the root-to-be, so if you want to build a whole
88 new root, you either have to save the existing one as a template and
89 restore it later, or restart again from scratch. This is not convenient,
90 - ptxdist (www.pengutronix.de/software/ptxdist), whose purpose is very
92 - other projects (openembedded.org for example), which are again used to
93 build root file systems.
95 crosstool-NG is really targeted at building toolchains, and only toolchains.
96 It is then up to you to use it the way you want.
104 crosstool was first 'conceived' by Dan Kegel, who offered it to the community
105 as a set of scripts, a repository of patches, and some pre-configured, general
106 purpose setup files to be used to configure crosstool. This is available at
107 http://www.kegel.com/crosstool, and the subversion repository is hosted on
108 google at http://code.google.com/p/crosstool/.
110 I once managed to add support for uClibc-based toolchains, but it did not make
111 into mainline, mostly because I didn't have time to port the patch forward to
112 the new versions, due in part to the big effort it was taking.
114 So I decided to clean up crosstool in the state it was, re-order the things
115 in place, add appropriate support for what I needed, that is uClibc support
116 and a menu-driven configuration, named the new implementation crosstool-NG,
117 (standing for crosstool Next Generation, as many other comunity projects do,
118 and as a wink at the TV series "Star Trek: The Next Generation" ;-) ) and
119 made it available to the community, in case it was of interest to any one.
122 _____________________________
124 Referring to crosstool-NG /
125 __________________________/
128 The long name of the project is crosstool-NG:
129 * no leading uppercase (except as first word in a sentence)
130 * crosstool and NG separated with a hyphen (dash)
133 Crosstool-NG can also be referred to by its short name CT-NG:
135 * CT and NG separated with a hyphen (dash)
137 The long name is preferred over the short name, except in mail subjects, where
138 the short name is a better fit.
140 When referring to a specific version of crosstool-NG, append the version number
143 - the long name, a space, and the version string
145 - the long name in lowercase, a hyphen (dash), and the version string
146 - this is used to name the release tarballs
147 * crosstool-ng-X.Y.Z+hg_id
148 - the long name in lowercase, a hyphen, the version string, and the Hg id
149 (as returned by: ct-ng version)
150 - this is used to differentiate between releases and snapshots
152 The frontend to crosstool-NG is the command ct-ng:
154 * ct and ng separated by a hyphen (dash)
157 ___________________________
159 Installing crosstool-NG /
160 ________________________/
162 There are two ways you can use crosstool-NG:
163 - build and install it, then get rid of the sources like you'd do for most
165 - or only build it and run from the source directory.
167 The former should be used if you got crosstool-NG from a packaged tarball, see
168 "Install method", below, while the latter is most useful for developpers that
169 use a clone of the repository, and want to submit patches, see "The Hacker's
175 If you go for the install, then you just follow the classical, but yet easy
177 ./configure --prefix=/some/place
180 export PATH="${PATH}:/some/place/bin"
182 You can then get rid of crosstool-NG source. Next create a directory to serve
183 as a working place, cd in there and run:
186 See below for complete usage.
191 If you go the hacker's way, then the usage is a bit different, although very
196 Now, *do not* remove crosstool-NG sources. They are needed to run crosstool-NG!
197 Stay in the directory holding the sources, and run:
200 See below for complete usage.
202 Now, provided you used a clone of the repository, you can send me your changes.
203 See the section titled CONTRIBUTING, below, for how to submit changees.
205 Preparing for packaging |
206 ------------------------+
208 If you plan on packaging crosstool-NG, you surely don't want to install it
209 in your root file system. The install procedure of crosstool-NG honors the
212 ./configure --prefix=/usr
214 make DESTDIR=/packaging/place install
219 crosstool-NG comes with a shell script fragment that defines bash-compatible
220 completion. That shell fragment is currently not installed automatically, but
223 To install the shell script fragment, you have two options:
224 - install system-wide, most probably by copying ct-ng.comp into
225 /etc/bash_completion.d/
226 - install for a single user, by copying ct-ng.comp into ${HOME}/ and
227 sourcing this file from your ${HOME}/.bashrc
232 Some people contibuted code that couldn't get merged for various reasons. This
233 code is available as lzma-compressed patches, in the contrib/ sub-directory.
234 These patches are to be applied to the source of crosstool-NG, prior to
235 installing, using something like the following:
236 lzcat contrib/foobar.patch.lzma |patch -p1
238 There is no guarantee that a particuliar contribution applies to the current
239 version of crosstool-ng, or that it will work at all. Use contributions at
243 ____________________________
245 Configuring crosstool-NG /
246 _________________________/
248 crosstool-NG is configured with a configurator presenting a menu-stuctured set
249 of options. These options let you specify the way you want your toolchain
250 built, where you want it installed, what architecture and specific processor it
251 will support, the version of the components you want to use, etc... The
252 value for those options are then stored in a configuration file.
254 The configurator works the same way you configure your Linux kernel. It is
255 assumed you now how to handle this.
257 To enter the menu, type:
260 Almost every config item has a help entry. Read them carefully.
262 String and number options can refer to environment variables. In such a case,
263 you must use the shell syntax: ${VAR}. You shall neither single- nor double-
264 quote the string/number options.
266 There are three environment variables that are computed by crosstool-NG, and
270 It represents the target tuple you are building for. You can use it for
271 example in the installation/prefix directory, such as:
272 /opt/x-tools/${CT_TARGET}
275 The top directory where crosstool-NG is running. You shouldn't need it in
276 most cases. There is one case where you may need it: if you have local
277 patches and you store them in your running directory, you can refer to them
278 by using CT_TOP_DIR, such as:
279 ${CT_TOP_DIR}/patches.myproject
282 The version of crosstool-NG you are using. Not much use for you, but it's
283 there if you need it.
285 Interesting config options |
286 ---------------------------+
288 CT_LOCAL_TARBALLS_DIR:
289 If you already have some tarballs in a direcotry, enter it here. That will
290 speed up the retrieving phase, where crosstool-NG would otherwise download
294 This is where the toolchain will be installed in (and for now, where it
295 will run from). Common use is to add the target tuple in the directory
296 path, such as (see above):
297 /opt/x-tools/${CT_TARGET}
300 An identifier for your toolchain, will take place in the vendor part of the
301 target tuple. It shall *not* contain spaces or dashes. Usually, keep it
302 to a one-word string, or use underscores to separate words if you need.
303 Avoid dots, commas, and special characters.
306 An alias for the toolchian. It will be used as a prefix to the toolchain
307 tools. For example, you will have ${CT_TARGET_ALIAS}-gcc
309 Also, if you think you don't see enough versions, you can try to enable one of
313 Show obsolete versions or tools. Most of the time, you don't want to base
314 your toolchain on too old a version (of gcc, for example). But at times, it
315 can come handy to use such an old version for regression tests. Those old
316 versions are hidden behind CT_OBSOLETE. Those versions (or features) are so
317 marked because maintaining support for those in crosstool-NG would be too
318 costly, time-wise, and time is dear.
321 Show experimental versions or tools. Again, you might not want to base your
322 toolchain on too recent tools (eg. gcc) for production. But if you need a
323 feature present only in a recent version, or a new tool, you can find them
324 hidden behind CT_EXPERIMENTAL. Those versions (or features) did not (yet)
325 receive thorough testing in crosstool-NG, and/or are not mature enough to
328 Re-building an existing toolchain |
329 ----------------------------------+
331 If you have an existing toolchain, you can re-use the options used to build it
332 to create a new toolchain. That needs a very little bit of effort on your side
333 but is quite easy. The options to build a toolchain are saved with the
334 toolchain, and you can retrieve this configuration by running:
335 ${CT_TARGET}-ct-ng.config
337 An alternate method is to extract the configuration from a build.log file.
338 This will be necessary if your toolchain was build with crosstool-NG prior
339 to 1.4.0, but can be used with build.log files from any version:
340 ct-ng extractconfig <build.log >.config
342 Or, if your build.log file is compressed (most probably!):
343 bzcat build.log.bz2 |ct-ng extractconfig >.config
345 The above commands will dump the configuration to stdout, so to rebuild a
346 toolchain with this configuration, just redirect the output to the
348 ${CT_TARGET}-ct-ng.config >.config
351 Then, you can review and change the configuration by running:
354 Using as a backend for a build-system |
355 --------------------------------------+
357 Crosstool-NG can be used as a backend for an automated build-system. In this
358 case, some components that are expected to run on the target (eg. the native
359 gdb, ltrace, DUMA...) are not available in the menuconfig, and they are not
360 build either, as it is considered the responsibility of the build-system to
361 build its own versions of those tools.
363 If you want to use crosstool-NG as a backend to generate your toolchains for
364 your build-system, you have to set and export this environment variable:
367 (case is not sensitive, you can say Y).
370 ________________________
372 Running crosstool-NG /
373 _____________________/
375 To build the toolchain, simply type:
378 This will use the above configuration to retrieve, extract and patch the
379 components, build, install and eventually test your newly built toolchain.
381 You are then free to add the toolchain /bin directory in your PATH to use
384 In any case, you can get some terse help. Just type:
389 Stopping and restarting a build |
390 --------------------------------+
392 If you want to stop the build after a step you are debugging, you can pass the
393 variable STOP to make:
394 ct-ng build STOP=some_step
396 Conversely, if you want to restart a build at a specific step you are
397 debugging, you can pass the RESTART variable to make:
398 ct-ng build RESTART=some_step
400 Alternatively, you can call make with the name of a step to just do that step:
403 ct-ng build RESTART=libc_headers STOP=libc_headers
405 The shortcuts +step_name and step_name+ allow to respectively stop or restart
407 ct-ng +libc_headers and: ct-ng libc_headers+
409 ct-ng build STOP=libc_headers and: ct-ng build RESTART=libc_headers
411 To obtain the list of acceptable steps, please call:
414 Note that in order to restart a build, you'll have to say 'Y' to the config
415 option CT_DEBUG_CT_SAVE_STEPS, and that the previous build effectively went
418 Building all toolchains at once |
419 --------------------------------+
421 You can build all samples; simply call:
424 Overriding the number of // jobs |
425 ---------------------------------+
427 If you want to override the number of jobs to run in // (the -j option to
428 make), you can either re-enter the menuconfig, or simply add it on the command
432 which tells crosstool-NG to override the number of // jobs to 4.
434 You can see the actions that support overriding the number of // jobs in
435 the help menu. Those are the ones with [.#] after them (eg. build[.#] or
436 build-all[.#], and so on...).
441 The crosstool-NG script 'ct-ng' is a Makefile-script. It does *not* execute
442 in parallel (there is not much to gain). When speaking of // jobs, we are
443 refering to the number of // jobs when making the *components*. That is, we
444 speak of the number of // jobs used to build gcc, glibc, and so on...
449 Starting with gcc-4.3 come two new dependencies: GMP and MPFR. With gcc-4.4,
450 come three new ones: GMP, PPL and CLooG/ppl. These are libraries that enable
451 advanced features to gcc. Additionally, some of the libraries can be used by
452 binutils and gdb. Unfortunately, not all systems on which crosstool-NG runs
453 have all of those libraries. And for those that do, the versions of those
454 libraries may be older than the version required by gcc.
456 This is why crosstool-NG builds its own set of libraries as part of the
459 The libraries are built as shared libraries, because building them as static
460 libraries has some short-comings. This poses no problem at build time, as
461 crosstool-NG correctly points gcc (and binutils and gdb) to the correct
462 place where our own version of the libraries are installed. But it poses
463 a problem when gcc et al. are run: the place where the libraries are is most
464 probably not known to the host dynamic linker. Still worse, if the host system
465 has its own versions, then ld.so would load the wrong library!
467 So we have to force the dynamic linker to load the correct version. We do this
468 by using the LD_LIBRARY_PATH variable, that informs the dynamic linker where
469 to look for shared libraries prior to searching its standard places. But we
470 can't impose that burden on all the system (because it'd be a nightmare to
471 configure, and because two toolchains on the same system may use different
472 versions of the libraries); so we have to do it on a per-toolchain basis.
474 So we rename all binaries of the toolchain (by adding a dot '.' as their first
475 character), and add a small program, the so-called "tools wrapper", that
476 correctly sets LD_LIBRARY_PATH prior to running the real tool.
478 First, the wrapper was written as a POSIX-compliant shell script. That shell
479 script is very simple, if not trivial, and works great. The only drawback is
480 that it does not work on host systems that lack a shell, for example the
481 MingW32 environment. To solve the issue, the wrapper has been re-written in C,
482 and compiled at build time. This C wrapper is much more complex than the shell
483 script, and although it sems to be working, it's been only lightly tested.
484 Some of the expected short-comings with this C wrapper are;
485 - multi-byte file names may not be handled correctly
486 - it's really big for what it does
488 So, the default wrapper installed with your toolchain is the shell script.
489 If you know that your system is missing a shell, then you shall use the C
490 wrapper (and report back whether it works, or does not work, for you).
493 _______________________
495 Using the toolchain /
496 ____________________/
498 Using the toolchain is as simple as adding the toolchain's bin directory in
500 export PATH="${PATH}:/your/toolchain/path/bin"
502 and then using the target tuple to tell the build systems to use your
504 ./configure --target=your-target-tuple
506 make CC=your-target-tuple-gcc
508 make CROSS_COMPILE=your-target-tuple-
511 It is strongly advised not to use the toolchain sys-root directory as an
512 install directory for your programs/packages. If you do so, you will not be
513 able to use your toolchain for another project. It is even strongly advised
514 that your toolchain is chmod-ed to read-only once successfully build, so that
515 you don't go polluting your toolchain with your programs/packages' files.
517 Thus, when you build a program/package, install it in a separate directory,
518 eg. /your/root. This directory is the /image/ of what would be in the root file
519 system of your target, and will contain all that your programs/packages have
522 The 'populate' script |
523 ----------------------+
525 When your root directory is ready, it is still missing some important bits: the
526 toolchain's libraries. To populate your root directory with those libs, just
528 your-target-tuple-populate -s /your/root -d /your/root-populated
530 This will copy /your/root into /your/root-populated, and put the needed and only
531 the needed libraries there. Thus you don't polute /your/root with any cruft that
532 would no longer be needed should you have to remove stuff. /your/root always
533 contains only those things you install in it.
535 You can then use /your/root-populated to build up your file system image, a
536 tarball, or to NFS-mount it from your target, or whatever you need.
538 The populate script accepts the following options:
541 Use 'src_dir' as the un-populated root directory.
544 Put the populated root directory in 'dst_dir'.
547 Always add specified libraries.
550 Always add libraries listed in 'file'.
553 Remove 'dst_dir' if it previously existed; continue even if any library
554 specified with -l or -L is missing.
557 Be verbose, and tell what's going on (you can see exactly where libs are
563 See 'your-target-tuple-populate -h' for more information on the options.
565 Here is how populate works:
567 1) performs some sanity checks:
568 - src_dir and dst_dir are specified
570 - unless forced, dst_dir does not exist
573 2) copy src_dir to dst_dir
575 3) add forced libraries to dst_dir
576 - build the list from -l and -L options
577 - get forced libraries from the sysroot (see below for heuristics)
578 - abort on the first missing library, unless -f is specified
580 4) add all missing libraries to dst_dir
581 - scan dst_dir for every ELF files that are 'executable' or
583 - list the "NEEDED Shared library" fields
584 - check if the library is already in dst_dir/lib or dst_dir/usr/lib
585 - if not, get the library from the sysroot
586 - if it's in sysroot/lib, copy it to dst_dir/lib
587 - if it's in sysroot/usr/lib, copy it to dst_dir/usr/lib
588 - in both cases, use the SONAME of the library to create the file
590 - if it was not found in the sysroot, this is an error.
598 There are four kinds of toolchains you could encounter.
600 First off, you must understand the following: when it comes to compilers there
601 are up to four machines involved:
602 1) the machine configuring the toolchain components: the config machine
603 2) the machine building the toolchain components: the build machine
604 3) the machine running the toolchain: the host machine
605 4) the machine the toolchain is generating code for: the target machine
607 We can most of the time assume that the config machine and the build machine
608 are the same. Most of the time, this will be true. The only time it isn't
609 is if you're using distributed compilation (such as distcc). Let's forget
610 this for the sake of simplicity.
612 So we're left with three machines:
617 Any toolchain will involve those three machines. You can be as pretty sure of
618 this as "2 and 2 are 4". Here is how they come into play:
620 1) build == host == target
621 This is a plain native toolchain, targetting the exact same machine as the
622 one it is built on, and running again on this exact same machine. You have
623 to build such a toolchain when you want to use an updated component, such
624 as a newer gcc for example.
625 crosstool-NG calls it "native".
627 2) build == host != target
628 This is a classic cross-toolchain, which is expected to be run on the same
629 machine it is compiled on, and generate code to run on a second machine,
631 crosstool-NG calls it "cross".
633 3) build != host == target
634 Such a toolchain is also a native toolchain, as it targets the same machine
635 as it runs on. But it is build on another machine. You want such a
636 toolchain when porting to a new architecture, or if the build machine is
637 much faster than the host machine.
638 crosstool-NG calls it "cross-native".
640 4) build != host != target
641 This one is called a canadian-toolchain (*), and is tricky. The three
642 machines in play are different. You might want such a toolchain if you
643 have a fast build machine, but the users will use it on another machine,
644 and will produce code to run on a third machine.
645 crosstool-NG calls it "canadian".
647 crosstool-NG can build all these kinds of toolchains (or is aiming at it,
650 (*) The term Canadian Cross came about because at the time that these issues
651 were all being hashed out, Canada had three national political parties.
652 http://en.wikipedia.org/wiki/Cross_compiler
660 Sending a bug report |
661 ---------------------+
663 If you need to send a bug report, please send a mail with subject
664 prefixed with "[CT_NG]" with to following destinations:
665 TO: yann.morin.1998 (at) anciens.enib.fr
666 CC: crossgcc (at) sourceware.org
671 If you want to enhance crosstool-NG, there's a to-do list in the TODO file.
673 Patches should come with the appropriate SoB line. A SoB line is typically
675 Signed-off-by: John DOE <john.doe@somewhere.net>
677 The SoB line is clearly described in Documentation/SubmittingPatches , section
678 12, of your favourite Linux kernel source tree.
680 Then you'll need to correctly configure Mercurial. There are two extensions
681 that you may find usefull:
682 - mq : http://mercurial.selenic.com/wiki/MqExtension
683 - patchbomb : http://mercurial.selenic.com/wiki/PatchbombExtension
685 Commit messages should look like (without leading pipes):
686 |component: short, one-line description
688 |optional longer description
689 |on multiple lines if needed
691 Here is an example commit message (see revision a53a5e1d61db):
692 |comp-libs/cloog: fix building
694 |For CLooG/PPL 0.15.3, the directory name was simply cloog-ppl.
695 |For any later versions, the directory name does have the version, such as
698 Here's a typical hacking session:
699 hg clone http://ymorin.is-a-geek.org/hg/crosstool-ng crosstool-ng
702 hg qnew -D -U -e my_first_patch
703 *edit patch description*
704 *hack* *hack* *check* *fails* *hack* *hack* *check* *works*
706 *edit patch description, serving as commit message*
707 hg qnew -D -U -e my_second_patch
708 *edit patch description*
709 *hack* *hack* *check* *fails* *hack* *hack* *check* *works*
711 *edit patch description, serving as commit message*
712 hg email --outgoing --intro \
713 --from '"Your Full NAME" <your.email (at) your.domain>' \
714 --to '"Yann E. MORIN" <yann.morin.1998 (at) anciens.enib.fr>' \
715 --cc 'crossgcc (at) sourceware.org'
716 *edit introductory message*
718 *re-send if no answer for a few days*
720 Note: replace '(at)' above with a plain '@'.
728 Internally, crosstool-NG is script-based. To ease usage, the frontend is
734 The entry point to crosstool-NG is the Makefile script "ct-ng". Calling this
735 script with an action will act exactly as if the Makefile was in the current
736 working directory and make was called with the action as rule. Thus:
739 is equivalent to having the Makefile in CWD, and calling:
742 Having ct-ng as it is avoids copying the Makefile everywhere, and acts as a
745 ct-ng loads sub- Makefiles from the library directory $(CT_LIB_DIR), as set up
746 at configuration time with ./configure.
748 ct-ng also searches for config files, sub-tools, samples, scripts and patches in
749 that library directory.
751 Because of a stupid make behavior/bug I was unable to track down, implicit make
752 rules are disabled: installing with --local would triger those rules, and mconf
758 The kconfig language is a hacked version, vampirised from the Linux kernel
759 (http://www.kernel.org/), and (heavily) adapted to my needs.
761 The list of the most notable changes (at least the ones I remember) follows:
762 - the CONFIG_ prefix has been replaced with CT_
763 - a leading | in prompts is skipped, and subsequent leading spaces are not
764 trimmed; otherwise leading spaces are silently trimmed
765 - removed the warning about undefined environment variable
767 The kconfig parsers (conf and mconf) are not installed pre-built, but as
768 source files. Thus you can have the directory where crosstool-NG is installed,
769 exported (via NFS or whatever) and have clients with different architectures
770 use the same crosstool-NG installation, and most notably, the same set of
773 Architecture-specific |
774 ----------------------+
776 Note: this chapter is not really well written, and might thus be a little bit
777 complex to understand. To get a better grasp of what an architecture is, the
778 reader is kindly encouraged to look at the "arch/" sub-directory, and to the
779 existing architectures to see how things are laid out.
781 An architecture is defined by:
783 - a human-readable name, in lower case letters, with numbers as appropriate.
784 The underscore is allowed; space and special characters are not.
786 - a file in "config/arch/", named after the architecture's name, and suffixed
788 Eg.: config/arch/arm.in
789 - a file in "scripts/build/arch/", named after the architecture's name, and
791 Eg.: scripts/build/arch/arm.sh
793 The architecture's ".in" file API:
794 > the config option "ARCH_%arch%" (where %arch% is to be replaced with the
795 actual architecture name).
796 That config option must have *neither* a type, *nor* a prompt! Also, it can
797 *not* depend on any other config option (EXPERIMENTAL is managed as above).
801 defines a (terse) help entry for this architecture:
805 The ARM architecture.
807 selects adequate associated config options.
808 Note: 64-bit architectures *shall* select ARCH_64
811 select ARCH_SUPPORTS_BOTH_ENDIAN
812 select ARCH_DEFAULT_LE
814 The ARM architecture.
819 The x86_64 architecture.
821 > other target-specific options, at your discretion. Note however that to
822 avoid name-clashing, such options shall be prefixed with "ARCH_%arch%",
823 where %arch% is again replaced by the actual architecture name.
824 (Note: due to historical reasons, and lack of time to clean up the code,
825 I may have left some config options that do not completely conform to
826 this, as the architecture name was written all upper case. However, the
827 prefix is unique among architectures, and does not cause harm).
829 The architecture's ".sh" file API:
830 > the function "CT_DoArchTupleValues"
833 - all variables from the ".config" file,
834 - the two variables "target_endian_eb" and "target_endian_el" which are
835 the endianness suffixes
836 + return value: 0 upon success, !0 upon failure
839 - the environment variable CT_TARGET_ARCH
841 the architecture part of the target tuple.
842 Eg.: "armeb" for big endian ARM
846 - the environment variable CT_TARGET_SYS
848 the sytem part of the target tuple.
849 Eg.: "gnu" for glibc on most architectures
850 "gnueabi" for glibc on an ARM EABI
852 - for glibc-based toolchain: "gnu"
853 - for uClibc-based toolchain: "uclibc"
856 - the environment variables to configure the cross-gcc (defaults)
857 - CT_ARCH_WITH_ARCH : the gcc ./configure switch to select architecture level ( "--with-arch=${CT_ARCH_ARCH}" )
858 - CT_ARCH_WITH_ABI : the gcc ./configure switch to select ABI level ( "--with-abi=${CT_ARCH_ABI}" )
859 - CT_ARCH_WITH_CPU : the gcc ./configure switch to select CPU instruction set ( "--with-cpu=${CT_ARCH_CPU}" )
860 - CT_ARCH_WITH_TUNE : the gcc ./configure switch to select scheduling ( "--with-tune=${CT_ARCH_TUNE}" )
861 - CT_ARCH_WITH_FPU : the gcc ./configure switch to select FPU type ( "--with-fpu=${CT_ARCH_FPU}" )
862 - CT_ARCH_WITH_FLOAT : the gcc ./configure switch to select floating point arithmetics ( "--with-float=soft" or /empty/ )
865 - the environment variables to pass to the cross-gcc to build target binaries (defaults)
866 - CT_ARCH_ARCH_CFLAG : the gcc switch to select architecture level ( "-march=${CT_ARCH_ARCH}" )
867 - CT_ARCH_ABI_CFLAG : the gcc switch to select ABI level ( "-mabi=${CT_ARCH_ABI}" )
868 - CT_ARCH_CPU_CFLAG : the gcc switch to select CPU instruction set ( "-mcpu=${CT_ARCH_CPU}" )
869 - CT_ARCH_TUNE_CFLAG : the gcc switch to select scheduling ( "-mtune=${CT_ARCH_TUNE}" )
870 - CT_ARCH_FPU_CFLAG : the gcc switch to select FPU type ( "-mfpu=${CT_ARCH_FPU}" )
871 - CT_ARCH_FLOAT_CFLAG : the gcc switch to choose floating point arithmetics ( "-msoft-float" or /empty/ )
872 - CT_ARCH_ENDIAN_CFLAG : the gcc switch to choose big or little endian ( "-mbig-endian" or "-mlittle-endian" )
877 - the environement variables to configure the core and final compiler, specific to this architecture:
878 - CT_ARCH_CC_CORE_EXTRA_CONFIG : additional, architecture specific core gcc ./configure flags
879 - CT_ARCH_CC_EXTRA_CONFIG : additional, architecture specific final gcc ./configure flags
884 - the architecture-specific CFLAGS and LDFLAGS:
885 - CT_ARCH_TARGET_CLFAGS
886 - CT_ARCH_TARGET_LDFLAGS
890 You can have a look at "config/arch/arm.in" and "scripts/build/arch/arm.sh" for
891 a quite complete example of what an actual architecture description looks like.
896 A kernel is defined by:
898 - a human-readable name, in lower case letters, with numbers as appropriate.
899 The underscore is allowed; space and special characters are not (although
900 they are internally replaced with underscores.
901 Eg.: linux, bare-metal
902 - a file in "config/kernel/", named after the kernel name, and suffixed with
904 Eg.: config/kernel/linux.in, config/kernel/bare-metal.in
905 - a file in "scripts/build/kernel/", named after the kernel name, and suffixed
907 Eg.: scripts/build/kernel/linux.sh, scripts/build/kernel/bare-metal.sh
909 The kernel's ".in" file must contain:
910 > an optional lines containing exactly "# EXPERIMENTAL", starting on the
911 first column, and without any following space or other character.
912 If this line is present, then this kernel is considered EXPERIMENTAL,
913 and correct dependency on EXPERIMENTAL will be set.
915 > the config option "KERNEL_%kernel_name%" (where %kernel_name% is to be
916 replaced with the actual kernel name, with all special characters and
917 spaces replaced by underscores).
918 That config option must have *neither* a type, *nor* a prompt! Also, it can
919 *not* depends on EXPERIMENTAL.
920 Eg.: KERNEL_linux, KERNEL_bare_metal
922 defines a (terse) help entry for this kernel.
924 config KERNEL_bare_metal
926 Build a compiler for use without any kernel.
928 selects adequate associated config options.
930 config KERNEL_bare_metal
933 Build a compiler for use without any kernel.
935 > other kernel specific options, at your discretion. Note however that, to
936 avoid name-clashing, such options should be prefixed with
937 "KERNEL_%kernel_name%", where %kernel_name% is again tp be replaced with
938 the actual kernel name.
939 (Note: due to historical reasons, and lack of time to clean up the code,
940 I may have left some config options that do not completely conform to
941 this, as the kernel name was written all upper case. However, the prefix
942 is unique among kernels, and does not cause harm).
944 The kernel's ".sh" file API:
945 > is a bash script fragment
947 > defines the function CT_DoKernelTupleValues
948 + see the architecture's CT_DoArchTupleValues, except for:
949 + set the environment variable CT_TARGET_KERNEL, the kernel part of the
951 + return value: ignored
953 > defines the function "do_kernel_get":
956 - all variables from the ".config" file.
957 + return value: 0 for success, !0 for failure.
958 + behavior: download the kernel's sources, and store the tarball into
959 "${CT_TARBALLS_DIR}". To this end, a functions is available, that
960 abstracts downloading tarballs:
961 - CT_DoGet <tarball_base_name> <URL1 [URL...]>
962 Eg.: CT_DoGet linux-2.6.26.5 ftp://ftp.kernel.org/pub/linux/kernel/v2.6
963 Note: retrieving sources from svn, cvs, git and the likes is not supported
964 by CT_DoGet. You'll have to do this by hand, as it is done for eglibc in
965 "scripts/build/libc/eglibc.sh"
967 > defines the function "do_kernel_extract":
970 - all variables from the ".config" file,
971 + return value: 0 for success, !0 for failure.
972 + behavior: extract the kernel's tarball into "${CT_SRC_DIR}", and apply
973 required patches. To this end, a function is available, that abstracts
975 - CT_ExtractAndPatch <tarball_base_name>
976 Eg.: CT_ExtractAndPatch linux-2.6.26.5
978 > defines the function "do_kernel_headers":
981 - all variables from the ".config" file,
982 + return value: 0 for success, !0 for failure.
983 + behavior: install the kernel headers (if any) in "${CT_SYSROOT_DIR}/usr/include"
985 > defines any kernel-specific helper functions
986 These functions, if any, must be prefixed with "do_kernel_%CT_KERNEL%_",
987 where '%CT_KERNEL%' is to be replaced with the actual kernel name, to avoid
990 You can have a look at "config/kernel/linux.in" and "scripts/build/kernel/linux.sh"
991 as an example of what a complex kernel description looks like.
993 Adding a new version of a component |
994 ------------------------------------+
996 When a new component, such as the Linux kernel, gcc or any other is released,
997 adding the new version to crosstool-NG is quite easy. There is a script that
998 will do all that for you:
999 scripts/addToolVersion.sh
1001 Run it with no option to get some help.
1006 To Be Written later...