1 | One of the biggest challenges to getting started with embedded devices is that you |
2 | cannot just install a copy of Linux and expect to be able to compile a firmware. |
3 | Even if you did remember to install a compiler and every development tool offered, |
4 | you still would not have the basic set of tools needed to produce a firmware image. |
5 | The embedded device represents an entirely new hardware platform, which is |
6 | most of the time incompatible with the hardware on your development machine, so in a process called |
7 | cross compiling you need to produce a new compiler capable of generating code for |
8 | your embedded platform, and then use it to compile a basic Linux distribution to |
9 | run on your device. |
10 | |
11 | The process of creating a cross compiler can be tricky, it is not something that is |
12 | regularly attempted and so there is a certain amount of mystery and black magic |
13 | associated with it. In many cases when you are dealing with embedded devices you will |
14 | be provided with a binary copy of a compiler and basic libraries rather than |
15 | instructions for creating your own -- it is a time saving step but at the same time |
16 | often means you will be using a rather dated set of tools. Likewise, it is also common |
17 | to be provided with a patched copy of the Linux kernel from the board or chip vendor, |
18 | but this is also dated and it can be difficult to spot exactly what has been |
19 | modified to make the kernel run on the embedded platform. |
20 | |
21 | \subsection{Building an image} |
22 | |
23 | OpenWrt takes a different approach to building a firmware; downloading, patching |
24 | and compiling everything from scratch, including the cross compiler. To put it |
25 | in simpler terms, OpenWrt does not contain any executables or even sources, it is an |
26 | automated system for downloading the sources, patching them to work with the given |
27 | platform and compiling them correctly for that platform. What this means is that |
28 | just by changing the template, you can change any step in the process. |
29 | |
30 | As an example, if a new kernel is released, a simple change to one of the Makefiles |
31 | will download the latest kernel, patch it to run on the embedded platform and produce |
32 | a new firmware image -- there is no work to be done trying to track down an unmodified |
33 | copy of the existing kernel to see what changes had been made, the patches are |
34 | already provided and the process ends up almost completely transparent. This does not |
35 | just apply to the kernel, but to anything included with OpenWrt -- It is this one |
36 | simple understated concept which is what allows OpenWrt to stay on the bleeding edge |
37 | with the latest compilers, latest kernels and latest applications. |
38 | |
39 | So let's take a look at OpenWrt and see how this all works. |
40 | |
41 | |
42 | \subsubsection{Download OpenWrt} |
43 | |
44 | OpenWrt can be downloaded via subversion using the following command: |
45 | |
46 | \begin{Verbatim} |
47 | $ svn checkout svn://svn.openwrt.org/openwrt/trunk openwrt-trunk |
48 | \end{Verbatim} |
49 | |
50 | Additionally, there is a trac interface on \href{https://dev.openwrt.org/}{https://dev.openwrt.org/} |
51 | which can be used to monitor svn commits and browse the source repository. |
52 | |
53 | |
54 | \subsubsection{The directory structure} |
55 | |
56 | There are four key directories in the base: |
57 | |
58 | \begin{itemize} |
59 | \item \texttt{tools} |
60 | \item \texttt{toolchain} |
61 | \item \texttt{package} |
62 | \item \texttt{target} |
63 | \end{itemize} |
64 | |
65 | \texttt{tools} and \texttt{toolchain} refer to common tools which will be |
66 | used to build the firmware image, the compiler, and the C library. |
67 | The result of this is three new directories, \texttt{build\_dir/host}, which is a temporary |
68 | directory for building the target independent tools, \texttt{build\_dir/toolchain-\textit{<arch>}*} |
69 | which is used for building the toolchain for a specific architecture, and |
70 | \texttt{staging\_dir/toolchain-\textit{<arch>}*} where the resulting toolchain is installed. |
71 | You will not need to do anything with the toolchain directory unless you intend to |
72 | add a new version of one of the components above. |
73 | |
74 | \begin{itemize} |
75 | \item \texttt{build\_dir/host} |
76 | \item \texttt{build\_dir/toolchain-\textit{<arch>}*} |
77 | \end{itemize} |
78 | |
79 | \texttt{package} is for exactly that -- packages. In an OpenWrt firmware, almost everything |
80 | is an \texttt{.ipk}, a software package which can be added to the firmware to provide new |
81 | features or removed to save space. Note that packages are also maintained outside of the main |
82 | trunk and can be obtained from subversion using the package feeds system: |
83 | |
84 | \begin{Verbatim} |
85 | $ ./scripts/feeds update |
86 | \end{Verbatim} |
87 | |
88 | Those packages can be used to extend the functionality of the build system and need to be |
89 | symlinked into the main trunk. Once you do that, the packages will show up in the menu for |
90 | configuration. You would do something like this: |
91 | |
92 | \begin{Verbatim} |
93 | $ ./scripts/feeds search nmap |
94 | Search results in feed 'packages': |
95 | nmap Network exploration and/or security auditing utility |
96 | |
97 | $ ./scripts/feeds install nmap |
98 | \end{Verbatim} |
99 | |
100 | To include all packages, issue the following command: |
101 | |
102 | \begin{Verbatim} |
103 | $ make package/symlinks |
104 | \end{Verbatim} |
105 | |
106 | \texttt{target} refers to the embedded platform, this contains items which are specific to |
107 | a specific embedded platform. Of particular interest here is the "\texttt{target/linux}" |
108 | directory which is broken down by platform \textit{<arch>} and contains the patches to the |
109 | kernel, profile config, for a particular platform. There's also the "\texttt{target/image}" directory |
110 | which describes how to package a firmware for a specific platform. |
111 | |
112 | Both the target and package steps will use the directory "\texttt{build\_dir/\textit{<arch>}}" |
113 | as a temporary directory for compiling. Additionally, anything downloaded by the toolchain, |
114 | target or package steps will be placed in the "\texttt{dl}" directory. |
115 | |
116 | \begin{itemize} |
117 | \item \texttt{build\_dir/\textit{<arch>}} |
118 | \item \texttt{dl} |
119 | \end{itemize} |
120 | |
121 | \subsubsection{Building OpenWrt} |
122 | |
123 | While the OpenWrt build environment was intended mostly for developers, it also has to be |
124 | simple enough that an inexperienced end user can easily build his or her own customized firmware. |
125 | |
126 | Running the command "\texttt{make menuconfig}" will bring up OpenWrt's configuration menu |
127 | screen, through this menu you can select which platform you're targeting, which versions of |
128 | the toolchain you want to use to build and what packages you want to install into the |
129 | firmware image. Note that it will also check to make sure you have the basic dependencies for it |
130 | to run correctly. If that fails, you will need to install some more tools in your local environment |
131 | before you can begin. |
132 | |
133 | Similar to the linux kernel config, almost every option has three choices, |
134 | \texttt{y/m/n} which are represented as follows: |
135 | |
136 | \begin{itemize} |
137 | \item{\texttt{<*>} (pressing y)} \\ |
138 | This will be included in the firmware image |
139 | \item{\texttt{<M>} (pressing m)} \\ |
140 | This will be compiled but not included (for later install) |
141 | \item{\texttt{< >} (pressing n)} \\ |
142 | This will not be compiled |
143 | \end{itemize} |
144 | |
145 | After you've finished with the menu configuration, exit and when prompted, save your |
146 | configuration changes. |
147 | |
148 | If you want, you can also modify the kernel config for the selected target system. |
149 | simply run "\texttt{make kernel\_menuconfig}" and the build system will unpack the kernel sources |
150 | (if necessary), run menuconfig inside of the kernel tree, and then copy the kernel config |
151 | to \texttt{target/linux/\textit{<platform>}/config} so that it is preserved over |
152 | "\texttt{make clean}" calls. |
153 | |
154 | To begin compiling the firmware, type "\texttt{make}". By default |
155 | OpenWrt will only display a high level overview of the compile process and not each individual |
156 | command. |
157 | |
158 | \subsubsection{Example:} |
159 | |
160 | \begin{Verbatim} |
161 | make[2] toolchain/install |
162 | make[3] -C toolchain install |
163 | make[2] target/compile |
164 | make[3] -C target compile |
165 | make[4] -C target/utils prepare |
166 | |
167 | [...] |
168 | \end{Verbatim} |
169 | |
170 | This makes it easier to monitor which step it's actually compiling and reduces the amount |
171 | of noise caused by the compile output. To see the full output, run the command |
172 | "\texttt{make V=99}". |
173 | |
174 | During the build process, buildroot will download all sources to the "\texttt{dl}" |
175 | directory and will start patching and compiling them in the "\texttt{build\_dir/\textit{<arch>}}" |
176 | directory. When finished, the resulting firmware will be in the "\texttt{bin}" directory |
177 | and packages will be in the "\texttt{bin/packages}" directory. |
178 | |
179 | |
180 | \subsection{Creating packages} |
181 | |
182 | One of the things that we've attempted to do with OpenWrt's template system is make it |
183 | incredibly easy to port software to OpenWrt. If you look at a typical package directory |
184 | in OpenWrt you'll find several things: |
185 | |
186 | \begin{itemize} |
187 | \item \texttt{package/\textit{<name>}/Makefile} |
188 | \item \texttt{package/\textit{<name>}/patches} |
189 | \item \texttt{package/\textit{<name>}/files} |
190 | \end{itemize} |
191 | |
192 | The patches directory is optional and typically contains bug fixes or optimizations to |
193 | reduce the size of the executable. The package makefile is the important item, provides |
194 | the steps actually needed to download and compile the package. |
195 | |
196 | The files directory is also optional and typicall contains package specific startup scripts or default configuration files that can be used out of the box with OpenWrt. |
197 | |
198 | Looking at one of the package makefiles, you'd hardly recognize it as a makefile. |
199 | Through what can only be described as blatant disregard and abuse of the traditional |
200 | make format, the makefile has been transformed into an object oriented template which |
201 | simplifies the entire ordeal. |
202 | |
203 | Here for example, is \texttt{package/bridge/Makefile}: |
204 | |
205 | \begin{Verbatim}[frame=single,numbers=left] |
206 | |
207 | include $(TOPDIR)/rules.mk |
208 | |
209 | PKG_NAME:=bridge |
210 | PKG_VERSION:=1.0.6 |
211 | PKG_RELEASE:=1 |
212 | |
213 | PKG_SOURCE:=bridge-utils-$(PKG_VERSION).tar.gz |
214 | PKG_SOURCE_URL:=@SF/bridge |
215 | PKG_MD5SUM:=9b7dc52656f5cbec846a7ba3299f73bd |
216 | PKG_CAT:=zcat |
217 | |
218 | PKG_BUILD_DIR:=$(BUILD_DIR)/bridge-utils-$(PKG_VERSION) |
219 | |
220 | include $(INCLUDE_DIR)/package.mk |
221 | |
222 | define Package/bridge |
223 | SECTION:=net |
224 | CATEGORY:=Base system |
225 | TITLE:=Ethernet bridging configuration utility |
226 | URL:=http://bridge.sourceforge.net/ |
227 | endef |
228 | |
229 | define Package/bridge/description |
230 | Manage ethernet bridging: |
231 | a way to connect networks together to form a larger network. |
232 | endef |
233 | |
234 | define Build/Configure |
235 | $(call Build/Configure/Default, \ |
236 | --with-linux-headers="$(LINUX_DIR)" \ |
237 | ) |
238 | endef |
239 | |
240 | define Package/bridge/install |
241 | $(INSTALL_DIR) $(1)/usr/sbin |
242 | $(INSTALL_BIN) $(PKG_BUILD_DIR)/brctl/brctl $(1)/usr/sbin/ |
243 | endef |
244 | |
245 | $(eval $(call BuildPackage,bridge)) |
246 | \end{Verbatim} |
247 | |
248 | As you can see, there's not much work to be done; everything is hidden in other makefiles |
249 | and abstracted to the point where you only need to specify a few variables. |
250 | |
251 | \begin{itemize} |
252 | \item \texttt{PKG\_NAME} \\ |
253 | The name of the package, as seen via menuconfig and ipkg |
254 | \item \texttt{PKG\_VERSION} \\ |
255 | The upstream version number that we are downloading |
256 | \item \texttt{PKG\_RELEASE} \\ |
257 | The version of this package Makefile |
258 | \item \texttt{PKG\_SOURCE} \\ |
259 | The filename of the original sources |
260 | \item \texttt{PKG\_SOURCE\_URL} \\ |
261 | Where to download the sources from (no trailing slash), you can add multiple download sources by separating them with a \\ and a carriage return. |
262 | \item \texttt{PKG\_MD5SUM} \\ |
263 | A checksum to validate the download |
264 | \item \texttt{PKG\_CAT} \\ |
265 | How to decompress the sources (zcat, bzcat, unzip) |
266 | \item \texttt{PKG\_BUILD\_DIR} \\ |
267 | Where to compile the package |
268 | \end{itemize} |
269 | |
270 | The \texttt{PKG\_*} variables define where to download the package from; |
271 | \texttt{@SF} is a special keyword for downloading packages from sourceforge. There is also |
272 | another keyword of \texttt{@GNU} for grabbing GNU source releases. If any of the above mentionned download source fails, the OpenWrt mirrors will be used as source. |
273 | |
274 | The md5sum (if present) is used to verify the package was downloaded correctly and |
275 | \texttt{PKG\_BUILD\_DIR} defines where to find the package after the sources are |
276 | uncompressed into \texttt{\$(BUILD\_DIR)}. |
277 | |
278 | At the bottom of the file is where the real magic happens, "BuildPackage" is a macro |
279 | set up by the earlier include statements. BuildPackage only takes one argument directly -- |
280 | the name of the package to be built, in this case "\texttt{bridge}". All other information |
281 | is taken from the define blocks. This is a way of providing a level of verbosity, it's |
282 | inherently clear what the contents of the \texttt{description} template in |
283 | \texttt{Package/bridge} is, which wouldn't be the case if we passed this information |
284 | directly as the Nth argument to \texttt{BuildPackage}. |
285 | |
286 | \texttt{BuildPackage} uses the following defines: |
287 | |
288 | \textbf{\texttt{Package/\textit{<name>}}:} \\ |
289 | \texttt{\textit{<name>}} matches the argument passed to buildroot, this describes |
290 | the package the menuconfig and ipkg entries. Within \texttt{Package/\textit{<name>}} |
291 | you can define the following variables: |
292 | |
293 | \begin{itemize} |
294 | \item \texttt{SECTION} \\ |
295 | The section of package (currently unused) |
296 | \item \texttt{CATEGORY} \\ |
297 | Which menu it appears in menuconfig: Network, Sound, Utilities, Multimedia ... |
298 | \item \texttt{TITLE} \\ |
299 | A short description of the package |
300 | \item \texttt{URL} \\ |
301 | Where to find the original software |
302 | \item \texttt{MAINTAINER} (optional) \\ |
303 | Who to contact concerning the package |
304 | \item \texttt{DEPENDS} (optional) \\ |
305 | Which packages must be built/installed before this package. To reference a dependency defined in the |
306 | same Makefile, use \textit{<dependency name>}. If defined as an external package, use |
307 | \textit{+<dependency name>}. For a kernel version dependency use: \textit{@LINUX\_2\_<minor version>} |
308 | \item \texttt{BUILDONLY} (optional) \\ |
309 | Set this option to 1 if you do NOT want your package to appear in menuconfig. |
310 | This is useful for packages which are only used as build dependencies. |
311 | \end{itemize} |
312 | |
313 | \textbf{\texttt{Package/\textit{<name>}/conffiles} (optional):} \\ |
314 | A list of config files installed by this package, one file per line. |
315 | |
316 | \textbf{\texttt{Build/Prepare} (optional):} \\ |
317 | A set of commands to unpack and patch the sources. You may safely leave this |
318 | undefined. |
319 | |
320 | \textbf{\texttt{Build/Configure} (optional):} \\ |
321 | You can leave this undefined if the source doesn't use configure or has a |
322 | normal config script, otherwise you can put your own commands here or use |
323 | "\texttt{\$(call Build/Configure/Default,\textit{<first list of arguments, second list>})}" as above to |
324 | pass in additional arguments for a standard configure script. The first list of arguments will be passed |
325 | to the configure script like that: \texttt{--arg 1} \texttt{--arg 2}. The second list contains arguments that should be |
326 | defined before running the configure script such as autoconf or compiler specific variables. |
327 | |
328 | To make it easier to modify the configure command line, you can either extend or completely override the following variables: |
329 | \begin{itemize} |
330 | \item \texttt{CONFIGURE\_ARGS} \\ |
331 | Contains all command line arguments (format: \texttt{--arg 1} \texttt{--arg 2}) |
332 | \item \texttt{CONFIGURE\_VARS} \\ |
333 | Contains all environment variables that are passed to ./configure (format: \texttt{NAME="value"}) |
334 | \end{itemize} |
335 | |
336 | \textbf{\texttt{Build/Compile} (optional):} \\ |
337 | How to compile the source; in most cases you should leave this undefined. |
338 | |
339 | As with \texttt{Build/Configure} there are two variables that allow you to override |
340 | the make command line environment variables and flags: |
341 | \begin{itemize} |
342 | \item \texttt{MAKE\_FLAGS} \\ |
343 | Contains all command line arguments (typically variable overrides like \texttt{NAME="value"} |
344 | \item \texttt{MAKE\_VARS} \\ |
345 | Contains all environment variables that are passed to the make command |
346 | \end{itemize} |
347 | |
348 | \textbf{\texttt{Build/InstallDev} (optional):} \\ |
349 | If your package provides a library that needs to be made available to other packages, |
350 | you can use the \texttt{Build/InstallDev} template to copy it into the staging directory |
351 | which is used to collect all files that other packages might depend on at build time. |
352 | When it is called by the build system, two parameters are passed to it. \texttt{\$(1)} points to |
353 | the regular staging dir, typically \texttt{staging\_dir/\textit{ARCH}}, while \texttt{\$(2)} points |
354 | to \texttt{staging\_dir/host}. The host staging dir is only used for binaries, which are |
355 | to be executed or linked against on the host and its \texttt{bin/} subdirectory is included |
356 | in the \texttt{PATH} which is passed down to the build system processes. |
357 | Please use \texttt{\$(1)} and \texttt{\$(2)} here instead of the build system variables |
358 | \texttt{\$(STAGING\_DIR)} and \texttt{\$(STAGING\_DIR\_HOST)}, because the build system behavior |
359 | when staging libraries might change in the future to include automatic uninstallation. |
360 | |
361 | \textbf{\texttt{Package/\textit{<name>}/install}:} \\ |
362 | A set of commands to copy files out of the compiled source and into the ipkg |
363 | which is represented by the \texttt{\$(1)} directory. Note that there are currently |
364 | 4 defined install macros: |
365 | \begin{itemize} |
366 | \item \texttt{INSTALL\_DIR} \\ |
367 | install -d -m0755 |
368 | \item \texttt{INSTALL\_BIN} \\ |
369 | install -m0755 |
370 | \item \texttt{INSTALL\_DATA} \\ |
371 | install -m0644 |
372 | \item \texttt{INSTALL\_CONF} \\ |
373 | install -m0600 |
374 | \end{itemize} |
375 | |
376 | The reason that some of the defines are prefixed by "\texttt{Package/\textit{<name>}}" |
377 | and others are simply "\texttt{Build}" is because of the possibility of generating |
378 | multiple packages from a single source. OpenWrt works under the assumption of one |
379 | source per package Makefile, but you can split that source into as many packages as |
380 | desired. Since you only need to compile the sources once, there's one global set of |
381 | "\texttt{Build}" defines, but you can add as many "Package/<name>" defines as you want |
382 | by adding extra calls to \texttt{BuildPackage} -- see the dropbear package for an example. |
383 | |
384 | After you have created your \texttt{package/\textit{<name>}/Makefile}, the new package |
385 | will automatically show in the menu the next time you run "make menuconfig" and if selected |
386 | will be built automatically the next time "\texttt{make}" is run. |
387 | |
388 | \subsection{Creating binary packages} |
389 | |
390 | You might want to create binary packages and include them in the resulting images as packages. |
391 | To do so, you can use the following template, which basically sets to nothing the Configure and |
392 | Compile templates. |
393 | |
394 | \begin{Verbatim}[frame=single,numbers=left] |
395 | |
396 | include $(TOPDIR)/rules.mk |
397 | |
398 | PKG_NAME:=binpkg |
399 | PKG_VERSION:=1.0 |
400 | PKG_RELEASE:=1 |
401 | |
402 | PKG_SOURCE:=binpkg-$(PKG_VERSION).tar.gz |
403 | PKG_SOURCE_URL:=http://server |
404 | PKG_MD5SUM:=9b7dc52656f5cbec846a7ba3299f73bd |
405 | PKG_CAT:=zcat |
406 | |
407 | include $(INCLUDE_DIR)/package.mk |
408 | |
409 | define Package/binpkg |
410 | SECTION:=net |
411 | CATEGORY:=Network |
412 | TITLE:=Binary package |
413 | endef |
414 | |
415 | define Package/bridge/description |
416 | Binary package |
417 | endef |
418 | |
419 | define Build/Configure |
420 | endef |
421 | |
422 | define Build/Compile |
423 | endef |
424 | |
425 | define Package/bridge/install |
426 | $(INSTALL_DIR) $(1)/usr/sbin |
427 | $(INSTALL_BIN) $(PKG_BUILD_DIR)/* $(1)/usr/sbin/ |
428 | endef |
429 | |
430 | $(eval $(call BuildPackage,bridge)) |
431 | \end{Verbatim} |
432 | |
433 | Provided that the tarball which contains the binaries reflects the final |
434 | directory layout (/usr, /lib ...), it becomes very easy to get your package |
435 | look like one build from sources. |
436 | |
437 | Note that using the same technique, you can easily create binary pcakages |
438 | for your proprietary kernel modules as well. |
439 | |
440 | \subsection{Creating kernel modules packages} |
441 | |
442 | The OpenWrt distribution makes the distinction between two kind of kernel modules, those coming along with the mainline kernel, and the others available as a separate project. We will see later that a common template is used for both of them. |
443 | |
444 | For kernel modules that are part of the mainline kernel source, the makefiles are located in \textit{package/kernel/modules/*.mk} and they appear under the section "Kernel modules" |
445 | |
446 | For external kernel modules, you can add them to the build system just like if they were software packages by defining a KernelPackage section in the package makefile. |
447 | |
448 | Here for instance the Makefile for the I2C subsytem kernel modules : |
449 | |
450 | \begin{Verbatim}[frame=single,numbers=left] |
451 | |
452 | I2CMENU:=I2C Bus |
453 | |
454 | define KernelPackage/i2c-core |
455 | TITLE:=I2C support |
456 | DESCRIPTION:=Kernel modules for i2c support |
457 | SUBMENU:=$(I2CMENU) |
458 | KCONFIG:=CONFIG_I2C_CORE CONFIG_I2C_DEV |
459 | FILES:=$(MODULES_DIR)/kernel/drivers/i2c/*.$(LINUX_KMOD_SUFFIX) |
460 | AUTOLOAD:=$(call AutoLoad,50,i2c-core i2c-dev) |
461 | endef |
462 | $(eval $(call KernelPackage,i2c-core)) |
463 | \end{Verbatim} |
464 | |
465 | To group kernel modules under a common description in menuconfig, you might want to define a \textit{<description>MENU} variable on top of the kernel modules makefile. |
466 | |
467 | \begin{itemize} |
468 | \item \texttt{TITLE} \\ |
469 | The name of the module as seen via menuconfig |
470 | \item \texttt{DESCRIPTION} \\ |
471 | The description as seen via help in menuconfig |
472 | \item \texttt{SUBMENU} \\ |
473 | The sub menu under which this package will be seen |
474 | \item \texttt{KCONFIG} \\ |
475 | Kernel configuration option dependency. For external modules, remove it. |
476 | \item \texttt{FILES} \\ |
477 | Files you want to inlude to this kernel module package, separate with spaces. |
478 | \item \texttt{AUTOLOAD} \\ |
479 | Modules that will be loaded automatically on boot, the order you write them is the order they would be loaded. |
480 | \end{itemize} |
481 | |
482 | After you have created your \texttt{package/kernel/modules/\textit{<name>}.mk}, the new kernel modules package |
483 | will automatically show in the menu under "Kernel modules" next time you run "make menuconfig" and if selected |
484 | will be built automatically the next time "\texttt{make}" is run. |
485 | |
486 | \subsection{Conventions} |
487 | |
488 | There are a couple conventions to follow regarding packages: |
489 | |
490 | \begin{itemize} |
491 | \item \texttt{files} |
492 | \begin{enumerate} |
493 | \item configuration files follow the convention \\ |
494 | \texttt{\textit{<name>}.conf} |
495 | \item init files follow the convention \\ |
496 | \texttt{\textit{<name>}.init} |
497 | \end{enumerate} |
498 | \item \texttt{patches} |
499 | \begin{enumerate} |
500 | \item patches are numerically prefixed and named related to what they do |
501 | \end{enumerate} |
502 | \end{itemize} |
503 | |
504 | \subsection{Troubleshooting} |
505 | |
506 | If you find your package doesn't show up in menuconfig, try the following command to |
507 | see if you get the correct description: |
508 | |
509 | \begin{Verbatim} |
510 | TOPDIR=$PWD make -C package/<name> DUMP=1 V=99 |
511 | \end{Verbatim} |
512 | |
513 | If you're just having trouble getting your package to compile, there's a few |
514 | shortcuts you can take. Instead of waiting for make to get to your package, you can |
515 | run one of the following: |
516 | |
517 | \begin{itemize} |
518 | \item \texttt{make package/\textit{<name>}/clean V=99} |
519 | \item \texttt{make package/\textit{<name>}/install V=99} |
520 | \end{itemize} |
521 | |
522 | Another nice trick is that if the source directory under \texttt{build\_dir/\textit{<arch>}} |
523 | is newer than the package directory, it won't clobber it by unpacking the sources again. |
524 | If you were working on a patch you could simply edit the sources under the |
525 | \texttt{build\_dir/\textit{<arch>}/\textit{<source>}} directory and run the install command above, |
526 | when satisfied, copy the patched sources elsewhere and diff them with the unpatched |
527 | sources. A warning though - if you go modify anything under \texttt{package/\textit{<name>}} |
528 | it will remove the old sources and unpack a fresh copy. |
529 | |
530 | Other useful targets include: |
531 | |
532 | \begin{itemize} |
533 | \item \texttt{make package/\textit{<name>}/prepare V=99} |
534 | \item \texttt{make package/\textit{<name>}/compile V=99} |
535 | \item \texttt{make package/\textit{<name>}/configure V=99} |
536 | \end{itemize} |
537 | |
538 | |
539 | \subsection{Using build environments} |
540 | OpenWrt provides a means of building images for multiple configurations |
541 | which can use multiple targets in one single checkout. These \emph{environments} |
542 | store a copy of the .config file generated by \texttt{make menuconfig} and the contents |
543 | of the \texttt{./files} folder. |
544 | The script \texttt{./scripts/env} is used to manage these environments, it uses |
545 | \texttt{git} (which needs to be installed on your system) as backend for version control. |
546 | |
547 | The command |
548 | \begin{Verbatim} |
549 | ./scripts/env help |
550 | \end{Verbatim} |
551 | produces a short help text with a list of commands. |
552 | |
553 | To create a new environment named \texttt{current}, run the following command |
554 | \begin{Verbatim} |
555 | ./scripts/env new current |
556 | \end{Verbatim} |
557 | This will move your \texttt{.config} file and \texttt{./files} (if it exists) to |
558 | the \texttt{env/} subdirectory and create symlinks in the base folder. |
559 | |
560 | After running make menuconfig or changing things in files/, your current state will |
561 | differ from what has been saved before. To show these changes, use: |
562 | \begin{Verbatim} |
563 | ./scripts/env diff |
564 | \end{Verbatim} |
565 | |
566 | If you want to save these changes, run: |
567 | \begin{Verbatim} |
568 | ./scripts/env save |
569 | \end{Verbatim} |
570 | If you want to revert your changes to the previously saved copy, run: |
571 | \begin{Verbatim} |
572 | ./scripts/env revert |
573 | \end{Verbatim} |
574 | |
575 | If you want, you can now create a second environment using the \texttt{new} command. |
576 | It will ask you whether you want to make it a clone of the current environment (e.g. |
577 | for minor changes) or if you want to start with a clean version (e.g. for selecting |
578 | a new target). |
579 | |
580 | To switch to a different environment (e.g. \texttt{test1}), use: |
581 | \begin{Verbatim} |
582 | ./scripts/env switch test1 |
583 | \end{Verbatim} |
584 | |
585 | To rename the current branch to a new name (e.g. \texttt{test2}), use: |
586 | \begin{Verbatim} |
587 | ./scripts/env rename test2 |
588 | \end{Verbatim} |
589 | |
590 | If you want to get rid of environment switching and keep everything in the base directory |
591 | again, use: |
592 | \begin{Verbatim} |
593 | ./scripts/env clear |
594 | \end{Verbatim} |
595 | |