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:
336 This will dump the configuration to stdout, so to rebuild a toolchain with this
337 configuration, the following is all you need to do:
338 ${CT_TARGET}-config >.config
341 Then, you can review and change the configuration by running:
345 ________________________
347 Running crosstool-NG /
348 _____________________/
350 To build the toolchain, simply type:
353 This will use the above configuration to retrieve, extract and patch the
354 components, build, install and eventually test your newly built toolchain.
356 You are then free to add the toolchain /bin directory in your PATH to use
359 In any case, you can get some terse help. Just type:
364 Stopping and restarting a build |
365 --------------------------------+
367 If you want to stop the build after a step you are debugging, you can pass the
368 variable STOP to make:
369 ct-ng build STOP=some_step
371 Conversely, if you want to restart a build at a specific step you are
372 debugging, you can pass the RESTART variable to make:
373 ct-ng build RESTART=some_step
375 Alternatively, you can call make with the name of a step to just do that step:
378 ct-ng build RESTART=libc_headers STOP=libc_headers
380 The shortcuts +step_name and step_name+ allow to respectively stop or restart
382 ct-ng +libc_headers and: ct-ng libc_headers+
384 ct-ng build STOP=libc_headers and: ct-ng build RESTART=libc_headers
386 To obtain the list of acceptable steps, please call:
389 Note that in order to restart a build, you'll have to say 'Y' to the config
390 option CT_DEBUG_CT_SAVE_STEPS, and that the previous build effectively went
393 Building all toolchains at once |
394 --------------------------------+
396 You can build all samples; simply call:
399 Overriding the number of // jobs |
400 ---------------------------------+
402 If you want to override the number of jobs to run in // (the -j option to
403 make), you can either re-enter the menuconfig, or simply add it on the command
407 which tells crosstool-NG to override the number of // jobs to 4.
409 You can see the actions that support overriding the number of // jobs in
410 the help menu. Those are the ones with [.#] after them (eg. build[.#] or
411 build-all[.#], and so on...).
416 The crosstool-NG script 'ct-ng' is a Makefile-script. It does *not* execute
417 in parallel (there is not much to gain). When speaking of // jobs, we are
418 refering to the number of // jobs when making the *components*. That is, we
419 speak of the number of // jobs used to build gcc, glibc, and so on...
424 Starting with gcc-4.3 come two new dependencies: GMP and MPFR. With gcc-4.4,
425 come three new ones: GMP, PPL and CLooG/ppl. These are libraries that enable
426 advanced features to gcc. Additionally, some of the libraries can be used by
427 binutils and gdb. Unfortunately, not all systems on which crosstool-NG runs
428 have all of those libraries. And for those that do, the versions of those
429 libraries may be older than the version required by gcc.
431 This is why crosstool-NG builds its own set of libraries as part of the
434 The libraries are built as shared libraries, because building them as static
435 libraries has some short-comings. This poses no problem at build time, as
436 crosstool-NG correctly points gcc (and binutils and gdb) to the correct
437 place where our own version of the libraries are installed. But it poses
438 a problem when gcc et al. are run: the place where the libraries are is most
439 probably not known to the host dynamic linker. Still worse, if the host system
440 has its own versions, then ld.so would load the wrong library!
442 So we have to force the dynamic linker to load the correct version. We do this
443 by using the LD_LIBRARY_PATH variable, that informs the dynamic linker where
444 to look for shared libraries prior to searching its standard places. But we
445 can't impose that burden on all the system (because it'd be a nightmare to
446 configure, and because two toolchains on the same system may use different
447 versions of the libraries); so we have to do it on a per-toolchain basis.
449 So we rename all binaries of the toolchain (by adding a dot '.' as their first
450 character), and add a small program, the so-called "tools wrapper", that
451 correctly sets LD_LIBRARY_PATH prior to running the real tool.
453 First, the wrapper was written as a POSIX-compliant shell script. That shell
454 script is very simple, if not trivial, and works great. The only drawback is
455 that it does not work on host systems that lack a shell, for example the
456 MingW32 environment. To solve the issue, the wrapper has been re-written in C,
457 and compiled at build time. This C wrapper is much more complex than the shell
458 script, and although it sems to be working, it's been only lightly tested.
459 Some of the expected short-comings with this C wrapper are;
460 - multi-byte file names may not be handled correctly
461 - it's really big for what it does
463 So, the default wrapper installed with your toolchain is the shell script.
464 If you know that your system is missing a shell, then you shall use the C
465 wrapper (and report back whether it works, or does not work, for you).
468 _______________________
470 Using the toolchain /
471 ____________________/
473 Using the toolchain is as simple as adding the toolchain's bin directory in
475 export PATH="${PATH}:/your/toolchain/path/bin"
477 and then using the target tuple to tell the build systems to use your
479 ./configure --target=your-target-tuple
481 make CC=your-target-tuple-gcc
483 make CROSS_COMPILE=your-target-tuple-
486 It is strongly advised not to use the toolchain sys-root directory as an
487 install directory for your programs/packages. If you do so, you will not be
488 able to use your toolchain for another project. It is even strongly advised
489 that your toolchain is chmod-ed to read-only once successfully build, so that
490 you don't go polluting your toolchain with your programs/packages' files.
492 Thus, when you build a program/package, install it in a separate directory,
493 eg. /your/root. This directory is the /image/ of what would be in the root file
494 system of your target, and will contain all that your programs/packages have
497 The 'populate' script |
498 ----------------------+
500 When your root directory is ready, it is still missing some important bits: the
501 toolchain's libraries. To populate your root directory with those libs, just
503 your-target-tuple-populate -s /your/root -d /your/root-populated
505 This will copy /your/root into /your/root-populated, and put the needed and only
506 the needed libraries there. Thus you don't polute /your/root with any cruft that
507 would no longer be needed should you have to remove stuff. /your/root always
508 contains only those things you install in it.
510 You can then use /your/root-populated to build up your file system image, a
511 tarball, or to NFS-mount it from your target, or whatever you need.
513 The populate script accepts the following options:
516 Use 'src_dir' as the un-populated root directory.
519 Put the populated root directory in 'dst_dir'.
522 Always add specified libraries.
525 Always add libraries listed in 'file'.
528 Remove 'dst_dir' if it previously existed; continue even if any library
529 specified with -l or -L is missing.
532 Be verbose, and tell what's going on (you can see exactly where libs are
538 See 'your-target-tuple-populate -h' for more information on the options.
540 Here is how populate works:
542 1) performs some sanity checks:
543 - src_dir and dst_dir are specified
545 - unless forced, dst_dir does not exist
548 2) copy src_dir to dst_dir
550 3) add forced libraries to dst_dir
551 - build the list from -l and -L options
552 - get forced libraries from the sysroot (see below for heuristics)
553 - abort on the first missing library, unless -f is specified
555 4) add all missing libraries to dst_dir
556 - scan dst_dir for every ELF files that are 'executable' or
558 - list the "NEEDED Shared library" fields
559 - check if the library is already in dst_dir/lib or dst_dir/usr/lib
560 - if not, get the library from the sysroot
561 - if it's in sysroot/lib, copy it to dst_dir/lib
562 - if it's in sysroot/usr/lib, copy it to dst_dir/usr/lib
563 - in both cases, use the SONAME of the library to create the file
565 - if it was not found in the sysroot, this is an error.
573 There are four kinds of toolchains you could encounter.
575 First off, you must understand the following: when it comes to compilers there
576 are up to four machines involved:
577 1) the machine configuring the toolchain components: the config machine
578 2) the machine building the toolchain components: the build machine
579 3) the machine running the toolchain: the host machine
580 4) the machine the toolchain is generating code for: the target machine
582 We can most of the time assume that the config machine and the build machine
583 are the same. Most of the time, this will be true. The only time it isn't
584 is if you're using distributed compilation (such as distcc). Let's forget
585 this for the sake of simplicity.
587 So we're left with three machines:
592 Any toolchain will involve those three machines. You can be as pretty sure of
593 this as "2 and 2 are 4". Here is how they come into play:
595 1) build == host == target
596 This is a plain native toolchain, targetting the exact same machine as the
597 one it is built on, and running again on this exact same machine. You have
598 to build such a toolchain when you want to use an updated component, such
599 as a newer gcc for example.
600 crosstool-NG calls it "native".
602 2) build == host != target
603 This is a classic cross-toolchain, which is expected to be run on the same
604 machine it is compiled on, and generate code to run on a second machine,
606 crosstool-NG calls it "cross".
608 3) build != host == target
609 Such a toolchain is also a native toolchain, as it targets the same machine
610 as it runs on. But it is build on another machine. You want such a
611 toolchain when porting to a new architecture, or if the build machine is
612 much faster than the host machine.
613 crosstool-NG calls it "cross-native".
615 4) build != host != target
616 This one is called a canadian-toolchain (*), and is tricky. The three
617 machines in play are different. You might want such a toolchain if you
618 have a fast build machine, but the users will use it on another machine,
619 and will produce code to run on a third machine.
620 crosstool-NG calls it "canadian".
622 crosstool-NG can build all these kinds of toolchains (or is aiming at it,
625 (*) The term Canadian Cross came about because at the time that these issues
626 were all being hashed out, Canada had three national political parties.
627 http://en.wikipedia.org/wiki/Cross_compiler
635 Sending a bug report |
636 ---------------------+
638 If you need to send a bug report, please send a mail with subject
639 prefixed with "[CT_NG]" with to following destinations:
640 TO: yann.morin.1998 (at) anciens.enib.fr
641 CC: crossgcc (at) sourceware.org
646 If you want to enhance crosstool-NG, there's a to-do list in the TODO file.
648 Patches should come with the appropriate SoB line. A SoB line is typically
650 Signed-off-by: John DOE <john.doe@somewhere.net>
652 The SoB line is clearly described in Documentation/SubmittingPatches , section
653 12, of your favourite Linux kernel source tree.
655 Then you'll need to correctly configure Mercurial. There are two extensions
656 that you may find usefull:
657 - mq : http://mercurial.selenic.com/wiki/MqExtension
658 - patchbomb : http://mercurial.selenic.com/wiki/PatchbombExtension
660 Commit messages should look like (without leading pipes):
661 |component: short, one-line description
663 |optional longer description
664 |on multiple lines if needed
666 Here is an example commit message (see revision a53a5e1d61db):
667 |comp-libs/cloog: fix building
669 |For CLooG/PPL 0.15.3, the directory name was simply cloog-ppl.
670 |For any later versions, the directory name does have the version, such as
673 Here's a typical hacking session:
674 hg clone http://ymorin.is-a-geek.org/hg/crosstool-ng crosstool-ng
677 hg qnew -D -U -e my_first_patch
678 *edit patch description*
679 *hack* *hack* *check* *fails* *hack* *hack* *check* *works*
681 *edit patch description, serving as commit message*
682 hg qnew -D -U -e my_second_patch
683 *edit patch description*
684 *hack* *hack* *check* *fails* *hack* *hack* *check* *works*
686 *edit patch description, serving as commit message*
687 hg email --outgoing --intro \
688 --from '"Your Full NAME" <your.email (at) your.domain>' \
689 --to '"Yann E. MORIN" <yann.morin.1998 (at) anciens.enib.fr>' \
690 --cc 'crossgcc (at) sourceware.org'
691 *edit introductory message*
693 *re-send if no answer for a few days*
695 Note: replace '(at)' above with a plain '@'.
703 Internally, crosstool-NG is script-based. To ease usage, the frontend is
709 The entry point to crosstool-NG is the Makefile script "ct-ng". Calling this
710 script with an action will act exactly as if the Makefile was in the current
711 working directory and make was called with the action as rule. Thus:
714 is equivalent to having the Makefile in CWD, and calling:
717 Having ct-ng as it is avoids copying the Makefile everywhere, and acts as a
720 ct-ng loads sub- Makefiles from the library directory $(CT_LIB_DIR), as set up
721 at configuration time with ./configure.
723 ct-ng also searches for config files, sub-tools, samples, scripts and patches in
724 that library directory.
726 Because of a stupid make behavior/bug I was unable to track down, implicit make
727 rules are disabled: installing with --local would triger those rules, and mconf
733 The kconfig language is a hacked version, vampirised from the Linux kernel
734 (http://www.kernel.org/), and (heavily) adapted to my needs.
736 The list of the most notable changes (at least the ones I remember) follows:
737 - the CONFIG_ prefix has been replaced with CT_
738 - a leading | in prompts is skipped, and subsequent leading spaces are not
740 - otherwise leading spaces are silently trimmed
742 The kconfig parsers (conf and mconf) are not installed pre-built, but as
743 source files. Thus you can have the directory where crosstool-NG is installed,
744 exported (via NFS or whatever) and have clients with different architectures
745 use the same crosstool-NG installation, and most notably, the same set of
748 Architecture-specific |
749 ----------------------+
751 Note: this chapter is not really well written, and might thus be a little bit
752 complex to understand. To get a better grasp of what an architecture is, the
753 reader is kindly encouraged to look at the "arch/" sub-directory, and to the
754 existing architectures to see how things are laid out.
756 An architecture is defined by:
758 - a human-readable name, in lower case letters, with numbers as appropriate.
759 The underscore is allowed; space and special characters are not.
761 - a file in "config/arch/", named after the architecture's name, and suffixed
763 Eg.: config/arch/arm.in
764 - a file in "scripts/build/arch/", named after the architecture's name, and
766 Eg.: scripts/build/arch/arm.sh
768 The architecture's ".in" file API:
769 > the config option "ARCH_%arch%" (where %arch% is to be replaced with the
770 actual architecture name).
771 That config option must have *neither* a type, *nor* a prompt! Also, it can
772 *not* depend on any other config option (EXPERIMENTAL is managed as above).
776 defines a (terse) help entry for this architecture:
780 The ARM architecture.
782 selects adequate associated config options.
783 Note: 64-bit architectures *shall* select ARCH_64
786 select ARCH_SUPPORTS_BOTH_ENDIAN
787 select ARCH_DEFAULT_LE
789 The ARM architecture.
794 The x86_64 architecture.
796 > other target-specific options, at your discretion. Note however that to
797 avoid name-clashing, such options shall be prefixed with "ARCH_%arch%",
798 where %arch% is again replaced by the actual architecture name.
799 (Note: due to historical reasons, and lack of time to clean up the code,
800 I may have left some config options that do not completely conform to
801 this, as the architecture name was written all upper case. However, the
802 prefix is unique among architectures, and does not cause harm).
804 The architecture's ".sh" file API:
805 > the function "CT_DoArchTupleValues"
808 - all variables from the ".config" file,
809 - the two variables "target_endian_eb" and "target_endian_el" which are
810 the endianness suffixes
811 + return value: 0 upon success, !0 upon failure
814 - the environment variable CT_TARGET_ARCH
816 the architecture part of the target tuple.
817 Eg.: "armeb" for big endian ARM
821 - the environment variable CT_TARGET_SYS
823 the sytem part of the target tuple.
824 Eg.: "gnu" for glibc on most architectures
825 "gnueabi" for glibc on an ARM EABI
827 - for glibc-based toolchain: "gnu"
828 - for uClibc-based toolchain: "uclibc"
831 - the environment variables to configure the cross-gcc (defaults)
832 - CT_ARCH_WITH_ARCH : the gcc ./configure switch to select architecture level ( "--with-arch=${CT_ARCH_ARCH}" )
833 - CT_ARCH_WITH_ABI : the gcc ./configure switch to select ABI level ( "--with-abi=${CT_ARCH_ABI}" )
834 - CT_ARCH_WITH_CPU : the gcc ./configure switch to select CPU instruction set ( "--with-cpu=${CT_ARCH_CPU}" )
835 - CT_ARCH_WITH_TUNE : the gcc ./configure switch to select scheduling ( "--with-tune=${CT_ARCH_TUNE}" )
836 - CT_ARCH_WITH_FPU : the gcc ./configure switch to select FPU type ( "--with-fpu=${CT_ARCH_FPU}" )
837 - CT_ARCH_WITH_FLOAT : the gcc ./configure switch to select floating point arithmetics ( "--with-float=soft" or /empty/ )
840 - the environment variables to pass to the cross-gcc to build target binaries (defaults)
841 - CT_ARCH_ARCH_CFLAG : the gcc switch to select architecture level ( "-march=${CT_ARCH_ARCH}" )
842 - CT_ARCH_ABI_CFLAG : the gcc switch to select ABI level ( "-mabi=${CT_ARCH_ABI}" )
843 - CT_ARCH_CPU_CFLAG : the gcc switch to select CPU instruction set ( "-mcpu=${CT_ARCH_CPU}" )
844 - CT_ARCH_TUNE_CFLAG : the gcc switch to select scheduling ( "-mtune=${CT_ARCH_TUNE}" )
845 - CT_ARCH_FPU_CFLAG : the gcc switch to select FPU type ( "-mfpu=${CT_ARCH_FPU}" )
846 - CT_ARCH_FLOAT_CFLAG : the gcc switch to choose floating point arithmetics ( "-msoft-float" or /empty/ )
847 - CT_ARCH_ENDIAN_CFLAG : the gcc switch to choose big or little endian ( "-mbig-endian" or "-mlittle-endian" )
852 - the environement variables to configure the core and final compiler, specific to this architecture:
853 - CT_ARCH_CC_CORE_EXTRA_CONFIG : additional, architecture specific core gcc ./configure flags
854 - CT_ARCH_CC_EXTRA_CONFIG : additional, architecture specific final gcc ./configure flags
859 - the architecture-specific CFLAGS and LDFLAGS:
860 - CT_ARCH_TARGET_CLFAGS
861 - CT_ARCH_TARGET_LDFLAGS
865 You can have a look at "config/arch/arm.in" and "scripts/build/arch/arm.sh" for
866 a quite complete example of what an actual architecture description looks like.
871 A kernel is defined by:
873 - a human-readable name, in lower case letters, with numbers as appropriate.
874 The underscore is allowed; space and special characters are not (although
875 they are internally replaced with underscores.
876 Eg.: linux, bare-metal
877 - a file in "config/kernel/", named after the kernel name, and suffixed with
879 Eg.: config/kernel/linux.in, config/kernel/bare-metal.in
880 - a file in "scripts/build/kernel/", named after the kernel name, and suffixed
882 Eg.: scripts/build/kernel/linux.sh, scripts/build/kernel/bare-metal.sh
884 The kernel's ".in" file must contain:
885 > an optional lines containing exactly "# EXPERIMENTAL", starting on the
886 first column, and without any following space or other character.
887 If this line is present, then this kernel is considered EXPERIMENTAL,
888 and correct dependency on EXPERIMENTAL will be set.
890 > the config option "KERNEL_%kernel_name%" (where %kernel_name% is to be
891 replaced with the actual kernel name, with all special characters and
892 spaces replaced by underscores).
893 That config option must have *neither* a type, *nor* a prompt! Also, it can
894 *not* depends on EXPERIMENTAL.
895 Eg.: KERNEL_linux, KERNEL_bare_metal
897 defines a (terse) help entry for this kernel.
899 config KERNEL_bare_metal
901 Build a compiler for use without any kernel.
903 selects adequate associated config options.
905 config KERNEL_bare_metal
908 Build a compiler for use without any kernel.
910 > other kernel specific options, at your discretion. Note however that, to
911 avoid name-clashing, such options should be prefixed with
912 "KERNEL_%kernel_name%", where %kernel_name% is again tp be replaced with
913 the actual kernel name.
914 (Note: due to historical reasons, and lack of time to clean up the code,
915 I may have left some config options that do not completely conform to
916 this, as the kernel name was written all upper case. However, the prefix
917 is unique among kernels, and does not cause harm).
919 The kernel's ".sh" file API:
920 > is a bash script fragment
922 > defines the function CT_DoKernelTupleValues
923 + see the architecture's CT_DoArchTupleValues, except for:
924 + set the environment variable CT_TARGET_KERNEL, the kernel part of the
926 + return value: ignored
928 > defines the function "do_kernel_get":
931 - all variables from the ".config" file.
932 + return value: 0 for success, !0 for failure.
933 + behavior: download the kernel's sources, and store the tarball into
934 "${CT_TARBALLS_DIR}". To this end, a functions is available, that
935 abstracts downloading tarballs:
936 - CT_DoGet <tarball_base_name> <URL1 [URL...]>
937 Eg.: CT_DoGet linux-2.6.26.5 ftp://ftp.kernel.org/pub/linux/kernel/v2.6
938 Note: retrieving sources from svn, cvs, git and the likes is not supported
939 by CT_DoGet. You'll have to do this by hand, as it is done for eglibc in
940 "scripts/build/libc/eglibc.sh"
942 > defines the function "do_kernel_extract":
945 - all variables from the ".config" file,
946 + return value: 0 for success, !0 for failure.
947 + behavior: extract the kernel's tarball into "${CT_SRC_DIR}", and apply
948 required patches. To this end, a function is available, that abstracts
950 - CT_ExtractAndPatch <tarball_base_name>
951 Eg.: CT_ExtractAndPatch linux-2.6.26.5
953 > defines the function "do_kernel_headers":
956 - all variables from the ".config" file,
957 + return value: 0 for success, !0 for failure.
958 + behavior: install the kernel headers (if any) in "${CT_SYSROOT_DIR}/usr/include"
960 > defines any kernel-specific helper functions
961 These functions, if any, must be prefixed with "do_kernel_%CT_KERNEL%_",
962 where '%CT_KERNEL%' is to be replaced with the actual kernel name, to avoid
965 You can have a look at "config/kernel/linux.in" and "scripts/build/kernel/linux.sh"
966 as an example of what a complex kernel description looks like.
968 Adding a new version of a component |
969 ------------------------------------+
971 When a new component, such as the Linux kernel, gcc or any other is released,
972 adding the new version to crosstool-NG is quite easy. There is a script that
973 will do all that for you:
974 scripts/addToolVersion.sh
976 Run it with no option to get some help.
981 To Be Written later...