From 972dcfcdbfe75dcfeb777150c136576cf1a71e99 Mon Sep 17 00:00:00 2001 From: Tudor Florea Date: Fri, 9 Oct 2015 22:59:03 +0200 Subject: initial commit for Enea Linux 5.0 arm Signed-off-by: Tudor Florea --- .../bitbake-user-manual-hello.xml | 506 +++++++++++++++++++++ 1 file changed, 506 insertions(+) create mode 100644 bitbake/doc/bitbake-user-manual/bitbake-user-manual-hello.xml (limited to 'bitbake/doc/bitbake-user-manual/bitbake-user-manual-hello.xml') diff --git a/bitbake/doc/bitbake-user-manual/bitbake-user-manual-hello.xml b/bitbake/doc/bitbake-user-manual/bitbake-user-manual-hello.xml new file mode 100644 index 0000000000..4ce7ed9f8c --- /dev/null +++ b/bitbake/doc/bitbake-user-manual/bitbake-user-manual-hello.xml @@ -0,0 +1,506 @@ + + + + Hello World Example + +
+ BitBake Hello World + + + The simplest example commonly used to demonstrate any new + programming language or tool is the + "Hello World" + example. + This appendix demonstrates, in tutorial form, Hello + World within the context of BitBake. + The tutorial describes how to create a new project + and the applicable metadata files necessary to allow + BitBake to build it. + +
+ +
+ Obtaining BitBake + + + See the + "Obtaining BitBake" + section for information on how to obtain BitBake. + Once you have the source code on your machine, the BitBake directory + appears as follows: + + $ ls -al + total 100 + drwxrwxr-x. 9 wmat wmat 4096 Jan 31 13:44 . + drwxrwxr-x. 3 wmat wmat 4096 Feb 4 10:45 .. + -rw-rw-r--. 1 wmat wmat 365 Nov 26 04:55 AUTHORS + drwxrwxr-x. 2 wmat wmat 4096 Nov 26 04:55 bin + drwxrwxr-x. 4 wmat wmat 4096 Jan 31 13:44 build + -rw-rw-r--. 1 wmat wmat 16501 Nov 26 04:55 ChangeLog + drwxrwxr-x. 2 wmat wmat 4096 Nov 26 04:55 classes + drwxrwxr-x. 2 wmat wmat 4096 Nov 26 04:55 conf + drwxrwxr-x. 3 wmat wmat 4096 Nov 26 04:55 contrib + -rw-rw-r--. 1 wmat wmat 17987 Nov 26 04:55 COPYING + drwxrwxr-x. 3 wmat wmat 4096 Nov 26 04:55 doc + -rw-rw-r--. 1 wmat wmat 69 Nov 26 04:55 .gitignore + -rw-rw-r--. 1 wmat wmat 849 Nov 26 04:55 HEADER + drwxrwxr-x. 5 wmat wmat 4096 Jan 31 13:44 lib + -rw-rw-r--. 1 wmat wmat 195 Nov 26 04:55 MANIFEST.in + -rwxrwxr-x. 1 wmat wmat 3195 Jan 31 11:57 setup.py + -rw-rw-r--. 1 wmat wmat 2887 Nov 26 04:55 TODO + + + + + At this point, you should have BitBake cloned to + a directory that matches the previous listing except for + dates and user names. + +
+ +
+ Setting Up the BitBake Environment + + + First, you need to be sure that you can run BitBake. + Set your working directory to where your local BitBake + files are and run the following command: + + $ ./bin/bitbake --version + BitBake Build Tool Core version 1.23.0, bitbake version 1.23.0 + + The console output tells you what version you are running. + + + + The recommended method to run BitBake is from a directory of your + choice. + To be able to run BitBake from any directory, you need to add the + executable binary to your binary to your shell's environment + PATH variable. + First, look at your current PATH variable + by entering the following: + + $ echo $PATH + + Next, add the directory location for the BitBake binary to the + PATH. + Here is an example that adds the + /home/scott-lenovo/bitbake/bin directory + to the front of the PATH variable: + + $ export PATH=/home/scott-lenovo/bitbake/bin:$PATH + + You should now be able to enter the bitbake + command from the command line while working from any directory. + +
+ +
+ The Hello World Example + + + The overall goal of this exercise is to build a + complete "Hello World" example utilizing task and layer + concepts. + Because this is how modern projects such as OpenEmbedded and + the Yocto Project utilize BitBake, the example + provides an excellent starting point for understanding + BitBake. + + + + To help you understand how to use BitBake to build targets, + the example starts with nothing but the bitbake + command, which causes BitBake to fail and report problems. + The example progresses by adding pieces to the build to + eventually conclude with a working, minimal "Hello World" + example. + + + + While every attempt is made to explain what is happening during + the example, the descriptions cannot cover everything. + You can find further information throughout this manual. + Also, you can actively participate in the + + discussion mailing list about the BitBake build tool. + + + + This example was inspired by and drew heavily from these sources: + + + Mailing List post - The BitBake equivalent of "Hello, World!" + + + Hambedded Linux blog post - From Bitbake Hello World to an Image + + + + + + As stated earlier, the goal of this example + is to eventually compile "Hello World". + However, it is unknown what BitBake needs and what you have + to provide in order to achieve that goal. + Recall that BitBake utilizes three types of metadata files: + Configuration Files, + Classes, and + Recipes. + But where do they go? + How does BitBake find them? + BitBake's error messaging helps you answer these types of questions + and helps you better understand exactly what is going on. + + + + Following is the complete "Hello World" example. + + + + Create a Project Directory: + First, set up a directory for the "Hello World" project. + Here is how you can do so in your home directory: + + $ mkdir ~/hello + $ cd ~/hello + + This is the directory that BitBake will use to do all of + its work. + You can use this directory to keep all the metafiles needed + by BitBake. + Having a project directory is a good way to isolate your + project. + + Run Bitbake: + At this point, you have nothing but a project directory. + Run the bitbake command and see what + it does: + + $ bitbake + The BBPATH variable is not set and bitbake did not + find a conf/bblayers.conf file in the expected location. + Maybe you accidentally invoked bitbake from the wrong directory? + DEBUG: Removed the following variables from the environment: + GNOME_DESKTOP_SESSION_ID, XDG_CURRENT_DESKTOP, + GNOME_KEYRING_CONTROL, DISPLAY, SSH_AGENT_PID, LANG, no_proxy, + XDG_SESSION_PATH, XAUTHORITY, SESSION_MANAGER, SHLVL, + MANDATORY_PATH, COMPIZ_CONFIG_PROFILE, WINDOWID, EDITOR, + GPG_AGENT_INFO, SSH_AUTH_SOCK, GDMSESSION, GNOME_KEYRING_PID, + XDG_SEAT_PATH, XDG_CONFIG_DIRS, LESSOPEN, DBUS_SESSION_BUS_ADDRESS, + _, XDG_SESSION_COOKIE, DESKTOP_SESSION, LESSCLOSE, DEFAULTS_PATH, + UBUNTU_MENUPROXY, OLDPWD, XDG_DATA_DIRS, COLORTERM, LS_COLORS + + The majority of this output is specific to environment variables + that are not directly relevant to BitBake. + However, the very first message regarding the + BBPATH variable and the + conf/bblayers.conf file + is relevant. + + When you run BitBake, it begins looking for metadata files. + The + BBPATH + variable is what tells BitBake where to look for those files. + BBPATH is not set and you need to set it. + Without BBPATH, Bitbake cannot + find any configuration files (.conf) + or recipe files (.bb) at all. + BitBake also cannot find the bitbake.conf + file. + + Setting BBPATH: + For this example, you can set BBPATH + in the same manner that you set PATH + earlier in the appendix. + You should realize, though, that it is much more flexible to set the + BBPATH variable up in a configuration + file for each project. + From your shell, enter the following commands to set and + export the BBPATH variable: + + $ BBPATH="<projectdirectory>" + $ export BBPATH + + Use your actual project directory in the command. + BitBake uses that directory to find the metadata it needs for + your project. + + When specifying your project directory, do not use the + tilde ("~") character as BitBake does not expand that character + as the shell would. + + + Run Bitbake: + Now that you have BBPATH defined, run + the bitbake command again: + + $ bitbake + ERROR: Traceback (most recent call last): + File "/home/scott-lenovo/bitbake/lib/bb/cookerdata.py", line 163, in wrapped + return func(fn, *args) + File "/home/scott-lenovo/bitbake/lib/bb/cookerdata.py", line 173, in parse_config_file + return bb.parse.handle(fn, data, include) + File "/home/scott-lenovo/bitbake/lib/bb/parse/__init__.py", line 99, in handle + return h['handle'](fn, data, include) + File "/home/scott-lenovo/bitbake/lib/bb/parse/parse_py/ConfHandler.py", line 120, in handle + abs_fn = resolve_file(fn, data) + File "/home/scott-lenovo/bitbake/lib/bb/parse/__init__.py", line 117, in resolve_file + raise IOError("file %s not found in %s" % (fn, bbpath)) + IOError: file conf/bitbake.conf not found in /home/scott-lenovo/hello + + ERROR: Unable to parse conf/bitbake.conf: file conf/bitbake.conf not found in /home/scott-lenovo/hello + + This sample output shows that BitBake could not find the + conf/bitbake.conf file in the project + directory. + This file is the first thing BitBake must find in order + to build a target. + And, since the project directory for this example is + empty, you need to provide a conf/bitbake.conf + file. + + Creating conf/bitbake.conf: + The conf/bitbake.conf includes a number of + configuration variables BitBake uses for metadata and recipe + files. + For this example, you need to create the file in your project directory + and define some key BitBake variables. + For more information on the bitbake.conf, + see + + + Use the following commands to create the conf + directory in the project directory: + + $ mkdir conf + + From within the conf directory, use + some editor to create the bitbake.conf + so that it contains the following: + + TMPDIR = "${TOPDIR}/tmp" + CACHE = "${TMPDIR}/cache" + STAMP = "${TMPDIR}/stamps" + T = "${TMPDIR}/work" + B = "${TMPDIR}" + + The TMPDIR variable establishes a directory + that BitBake uses for build output and intermediate files (other + than the cached information used by the + Setscene process. + Here, the TMPDIR directory is set to + hello/tmp. + Tip + You can always safely delete the tmp + directory in order to rebuild a BitBake target. + The build process creates the directory for you + when you run BitBake. + + For information about each of the other variables defined in this + example, click on the links to take you to the definitions in + the glossary. + + Run Bitbake: + After making sure that the conf/bitbake.conf + file exists, you can run the bitbake + command again: + +$ bitbake +ERROR: Traceback (most recent call last): + File "/home/scott-lenovo/bitbake/lib/bb/cookerdata.py", line 163, in wrapped + return func(fn, *args) + File "/home/scott-lenovo/bitbake/lib/bb/cookerdata.py", line 177, in _inherit + bb.parse.BBHandler.inherit(bbclass, "configuration INHERITs", 0, data) + File "/home/scott-lenovo/bitbake/lib/bb/parse/parse_py/BBHandler.py", line 92, in inherit + include(fn, file, lineno, d, "inherit") + File "/home/scott-lenovo/bitbake/lib/bb/parse/parse_py/ConfHandler.py", line 100, in include + raise ParseError("Could not %(error_out)s file %(fn)s" % vars(), oldfn, lineno) +ParseError: ParseError in configuration INHERITs: Could not inherit file classes/base.bbclass + +ERROR: Unable to parse base: ParseError in configuration INHERITs: Could not inherit file classes/base.bbclass + + In the sample output, BitBake could not find the + classes/base.bbclass file. + You need to create that file next. + + Creating classes/base.bbclass: + BitBake uses class files to provide common code and functionality. + The minimally required class for BitBake is the + classes/base.bbclass file. + The base class is implicitly inherited by + every recipe. + BitBake looks for the class in the classes + directory of the project (i.e hello/classes + in this example). + + Create the classes directory as follows: + + $ cd $HOME/hello + $ mkdir classes + + Move to the classes directory and then + create the base.bbclass file by inserting + this single line: + + addtask build + + The minimal task that BitBake runs is the + do_build task. + This is all the example needs in order to build the project. + Of course, the base.bbclass can have much + more depending on which build environments BitBake is + supporting. + For more information on the base.bbclass file, + you can look at + . + + Run Bitbake: + After making sure that the classes/base.bbclass + file exists, you can run the bitbake + command again: + + $ bitbake + Nothing to do. Use 'bitbake world' to build everything, or run 'bitbake --help' for usage information. + + BitBake is finally reporting no errors. + However, you can see that it really does not have anything + to do. + You need to create a recipe that gives BitBake something to do. + + Creating a Layer: + While it is not really necessary for such a small example, + it is good practice to create a layer in which to keep your + code separate from the general metadata used by BitBake. + Thus, this example creates and uses a layer called "mylayer". + + You can find additional information on adding a layer at + . + + + Minimally, you need a recipe file and a layer configuration + file in your layer. + The configuration file needs to be in the conf + directory inside the layer. + Use these commands to set up the layer and the conf + directory: + + $ cd $HOME + $ mkdir mylayer + $ cd mylayer + $ mkdir conf + + Move to the conf directory and create a + layer.conf file that has the following: + + BBPATH .= ":${LAYERDIR}" + + BBFILES += "${LAYERDIR}/*.bb" + + BBFILE_COLLECTIONS += "mylayer" + BBFILE_PATTERN_mylayer := "^${LAYERDIR}/" + + For information on these variables, click the links + to go to the definitions in the glossary. + You need to create the recipe file next. + Inside your layer at the top-level, use an editor and create + a recipe file named printhello.bb that + has the following: + + DESCRIPTION = "Prints Hello World" + PN = 'printhello' + PV = '1' + + python do_build() { + bb.plain("********************"); + bb.plain("* *"); + bb.plain("* Hello, World! *"); + bb.plain("* *"); + bb.plain("********************"); + } + + The recipe file simply provides a description of the + recipe, the name, version, and the do_build + task, which prints out "Hello World" to the console. + For more information on these variables, follow the links + to the glossary. + + Run Bitbake With a Target: + Now that a BitBake target exists, run the command and provide + that target: + + $ cd $HOME/hello + $ bitbake printhello + ERROR: no recipe files to build, check your BBPATH and BBFILES? + + Summary: There was 1 ERROR message shown, returning a non-zero exit code. + + We have created the layer with the recipe and the layer + configuration file but it still seems that BitBake cannot + find the recipe. + BitBake needs a conf/bblayers.conf that + lists the layers for the project. + Without this file, BitBake cannot find the recipe. + + Creating conf/bblayers.conf: + BitBake uses the conf/bblayers.conf file + to locate layers needed for the project. + This file must reside in the conf directory + of the project (i.e. hello/conf for this + example). + Set your working directory to the hello/conf + directory and then create the bblayers.conf + file so that it contains the following: + + BBLAYERS ?= " \ + /home/<you>/mylayer \ + " + + You need to provide your own information for + you in the file. + + Run Bitbake With a Target: + Now that you have supplied the bblayers.conf + file, run the bitbake command and provide + the target: + + $ bitbake printhello + Parsing recipes: 100% |##################################################################################| + Time: 00:00:00 + Parsing of 1 .bb files complete (0 cached, 1 parsed). 1 targets, 0 skipped, 0 masked, 0 errors. + NOTE: Resolving any missing task queue dependencies + NOTE: Preparing runqueue + NOTE: Executing RunQueue Tasks + ******************** + * * + * Hello, World! * + * * + ******************** + NOTE: Tasks Summary: Attempted 1 tasks of which 0 didn't need to be rerun and all succeeded. + + BitBake finds the printhello recipe and + successfully runs the task. + + After the first execution, re-running + bitbake printhello again will not + result in a BitBake run that prints the same console + output. + The reason for this is that the first time the + printhello.bb recipe's + do_build task executes + successfully, BitBake writes a stamp file for the task. + Thus, the next time you attempt to run the task + using that same bitbake command, + BitBake notices the stamp and therefore determines + that the task does not need to be re-run. + If you delete the tmp directory + or run bitbake -c clean printhello + and then re-run the build, the "Hello, World!" message will + be printed again. + + + +
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