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dev-manual, ref-manual: Consolidated debug info into dev-manual

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Fixes [YOCTO #12370]

Moved the debug information from the ref-manual to the dev-manual
where other debug information exists.  We now have a single area
(section) that deals with various debugging techniques and tips.

(From yocto-docs rev: 95394197fc04981bf7571e581ff8a0fd9c76223f)

Signed-off-by: Scott Rifenbark <srifenbark@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
This commit is contained in:
Scott Rifenbark
2018-01-16 10:59:43 -08:00
committed by Richard Purdie
parent 09e9f81c34
commit 0d52f18d39
5 changed files with 1460 additions and 1374 deletions
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documentation/dev-manual/dev-manual-common-tasks.xml
+1451 -467
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documentation/overview-manual/overview-concepts.xml
+2 -2
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@@ -1033,8 +1033,8 @@
<ulink url='&YOCTO_DOCS_REF_URL;#var-SSTATE_DIR'><filename>SSTATE_DIR</filename></ulink>. <ulink url='&YOCTO_DOCS_REF_URL;#var-SSTATE_DIR'><filename>SSTATE_DIR</filename></ulink>.
For information on how to view and interpret information in For information on how to view and interpret information in
<filename>siginfo</filename> files, see the <filename>siginfo</filename> files, see the
"<ulink url='&YOCTO_DOCS_REF_URL;#usingpoky-viewing-task-variable-dependencies'>Viewing Task Variable Dependencies</ulink>" "<ulink url='&YOCTO_DOCS_DEV_URL;#dev-viewing-task-variable-dependencies'>Viewing Task Variable Dependencies</ulink>"
section in the Yocto Project Reference Manual. section in the Yocto Project Development Tasks Manual.
</para> </para>
</section> </section>
documentation/overview-manual/overview-development-environment.xml
+2 -2
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@@ -2541,8 +2541,8 @@
<para> <para>
For details on how to view information about a task's For details on how to view information about a task's
signature, see the signature, see the
"<ulink url='&YOCTO_DOCS_REF_URL;#usingpoky-viewing-task-variable-dependencies'>Viewing Task Variable Dependencies</ulink>" "<ulink url='&YOCTO_DOCS_DEV_URL;#dev-viewing-task-variable-dependencies'>Viewing Task Variable Dependencies</ulink>"
section in the Yocto Project Reference Manual. section in the Yocto Project Development Tasks Manual.
</para> </para>
</section> </section>
documentation/ref-manual/ref-variables.xml
+5 -4
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@@ -9286,8 +9286,9 @@ recipes-graphics/xorg-font/font-alias_1.0.3.bb:PR = "${INC_PR}.3"
<filename>OVERRIDES</filename> in the output of the <filename>OVERRIDES</filename> in the output of the
<filename>bitbake -e</filename> command. <filename>bitbake -e</filename> command.
See the See the
"<link linkend='usingpoky-debugging-viewing-variable-values'>Viewing Variable Values</link>" "<ulink url='&YOCTO_DOCS_DEV_URL;#dev-debugging-viewing-variable-values'>Viewing Variable Values</ulink>"
section for more information. section in the Yocto Project Development Tasks
Manual for more information.
</note> </note>
</para> </para>
</glossdef> </glossdef>
@@ -10413,8 +10414,8 @@ recipes-graphics/xorg-font/font-alias_1.0.3.bb:PR = "${INC_PR}.3"
For examples of how this data is used, see the For examples of how this data is used, see the
"<ulink url='&YOCTO_DOCS_OVERVIEW_URL;#automatically-added-runtime-dependencies'>Automatically Added Runtime Dependencies</ulink>" "<ulink url='&YOCTO_DOCS_OVERVIEW_URL;#automatically-added-runtime-dependencies'>Automatically Added Runtime Dependencies</ulink>"
section in the Yocto Project Overview Manual and the section in the Yocto Project Overview Manual and the
"<link linkend='viewing-package-information-with-oe-pkgdata-util'>Viewing Package Information with <filename>oe-pkgdata-util</filename></link>" "<ulink url='&YOCTO_DOCS_DEV_URL;#viewing-package-information-with-oe-pkgdata-util'>Viewing Package Information with <filename>oe-pkgdata-util</filename></ulink>"
section elsewhere in this manual. section in the Yocto Project Development Tasks Manual.
</para> </para>
</glossdef> </glossdef>
</glossentry> </glossentry>
documentation/ref-manual/usingpoky.xml
-899
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@@ -11,905 +11,6 @@
documentation set provide more details on how to use the Yocto Project. documentation set provide more details on how to use the Yocto Project.
</para> </para>
<section id='usingpoky-debugging-tools-and-techniques'>
<title>Debugging Tools and Techniques</title>
<para>
The exact method for debugging build failures depends on the nature of
the problem and on the system's area from which the bug originates.
Standard debugging practices such as comparison against the last
known working version with examination of the changes and the
re-application of steps to identify the one causing the problem are
valid for the Yocto Project just as they are for any other system.
Even though it is impossible to detail every possible potential failure,
this section provides some general tips to aid in debugging.
</para>
<para>
A useful feature for debugging is the error reporting tool.
Configuring the Yocto Project to use this tool causes the
OpenEmbedded build system to produce error reporting commands as
part of the console output.
You can enter the commands after the build completes
to log error information
into a common database, that can help you figure out what might be
going wrong.
For information on how to enable and use this feature, see the
"<ulink url='&YOCTO_DOCS_DEV_URL;#using-the-error-reporting-tool'>Using the Error Reporting Tool</ulink>"
section in the Yocto Project Development Tasks Manual.
</para>
<para>
For discussions on debugging, see the
"<ulink url='&YOCTO_DOCS_DEV_URL;#platdev-gdb-remotedebug'>Debugging With the GNU Project Debugger (GDB) Remotely</ulink>" section
in the Yocto Project Development Tasks Manual
and the
"<ulink url='&YOCTO_DOCS_SDK_URL;#adt-eclipse'>Working within Eclipse</ulink>"
section in the Yocto Project Application Development and the
Extensible Software Development Kit (eSDK) manual.
</para>
<note>
The remainder of this section presents many examples of the
<filename>bitbake</filename> command.
You can learn about BitBake by reading the
<ulink url='&YOCTO_DOCS_BB_URL;#bitbake-user-manual'>BitBake User Manual</ulink>.
</note>
<section id='usingpoky-debugging-viewing-logs-from-failed-tasks'>
<title>Viewing Logs from Failed Tasks</title>
<para>
You can find the log for a task in the file
<filename>${</filename><link linkend='var-WORKDIR'><filename>WORKDIR</filename></link><filename>}/temp/log.do_</filename><replaceable>taskname</replaceable>.
For example, the log for the
<link linkend='ref-tasks-compile'><filename>do_compile</filename></link>
task of the QEMU minimal image for the x86 machine
(<filename>qemux86</filename>) might be in
<filename>tmp/work/qemux86-poky-linux/core-image-minimal/1.0-r0/temp/log.do_compile</filename>.
To see the commands
<link linkend='bitbake-term'>BitBake</link> ran
to generate a log, look at the corresponding
<filename>run.do_</filename><replaceable>taskname</replaceable>
file in the same directory.
</para>
<para>
<filename>log.do_</filename><replaceable>taskname</replaceable> and
<filename>run.do_</filename><replaceable>taskname</replaceable>
are actually symbolic links to
<filename>log.do_</filename><replaceable>taskname</replaceable><filename>.</filename><replaceable>pid</replaceable>
and
<filename>log.run_</filename><replaceable>taskname</replaceable><filename>.</filename><replaceable>pid</replaceable>,
where <replaceable>pid</replaceable> is the PID the task had when
it ran.
The symlinks always point to the files corresponding to the most
recent run.
</para>
</section>
<section id='usingpoky-debugging-viewing-variable-values'>
<title>Viewing Variable Values</title>
<para>
BitBake's <filename>-e</filename> option is used to display
variable values after parsing.
The following command displays the variable values after the
configuration files (i.e. <filename>local.conf</filename>,
<filename>bblayers.conf</filename>,
<filename>bitbake.conf</filename> and so forth) have been
parsed:
<literallayout class='monospaced'>
$ bitbake -e
</literallayout>
The following command displays variable values after a specific
recipe has been parsed.
The variables include those from the configuration as well:
<literallayout class='monospaced'>
$ bitbake -e recipename
</literallayout>
<note><para>
Each recipe has its own private set of variables (datastore).
Internally, after parsing the configuration, a copy of the
resulting datastore is made prior to parsing each recipe.
This copying implies that variables set in one recipe will
not be visible to other recipes.</para>
<para>Likewise, each task within a recipe gets a private
datastore based on the recipe datastore, which means that
variables set within one task will not be visible to
other tasks.</para>
</note>
</para>
<para>
In the output of <filename>bitbake -e</filename>, each variable is
preceded by a description of how the variable got its value,
including temporary values that were later overriden.
This description also includes variable flags (varflags) set on
the variable.
The output can be very helpful during debugging.
</para>
<para>
Variables that are exported to the environment are preceded by
<filename>export</filename> in the output of
<filename>bitbake -e</filename>.
See the following example:
<literallayout class='monospaced'>
export CC="i586-poky-linux-gcc -m32 -march=i586 --sysroot=/home/ulf/poky/build/tmp/sysroots/qemux86"
</literallayout>
</para>
<para>
In addition to variable values, the output of the
<filename>bitbake -e</filename> and
<filename>bitbake -e</filename>&nbsp;<replaceable>recipe</replaceable>
commands includes the following information:
<itemizedlist>
<listitem><para>
The output starts with a tree listing all configuration
files and classes included globally, recursively listing
the files they include or inherit in turn.
Much of the behavior of the OpenEmbedded build system
(including the behavior of the
<link linkend='normal-recipe-build-tasks'>normal recipe build tasks</link>)
is implemented in the
<link linkend='ref-classes-base'><filename>base</filename></link>
class and the classes it inherits, rather than being built
into BitBake itself.
</para></listitem>
<listitem><para>
After the variable values, all functions appear in the
output.
For shell functions, variables referenced within the
function body are expanded.
If a function has been modified using overrides or
using override-style operators like
<filename>_append</filename> and
<filename>_prepend</filename>, then the final assembled
function body appears in the output.
</para></listitem>
</itemizedlist>
</para>
</section>
<section id='viewing-package-information-with-oe-pkgdata-util'>
<title>Viewing Package Information with <filename>oe-pkgdata-util</filename></title>
<para>
You can use the <filename>oe-pkgdata-util</filename> command-line
utility to query
<link linkend='var-PKGDATA_DIR'><filename>PKGDATA_DIR</filename></link>
and display various package-related information.
When you use the utility, you must use it to view information
on packages that have already been built.
</para>
<para>
Following are a few of the available
<filename>oe-pkgdata-util</filename> subcommands.
<note>
You can use the standard * and ? globbing wildcards as part of
package names and paths.
</note>
<itemizedlist>
<listitem><para>
<filename>oe-pkgdata-util list-pkgs [</filename><replaceable>pattern</replaceable><filename>]</filename>:
Lists all packages that have been built, optionally
limiting the match to packages that match
<replaceable>pattern</replaceable>.
</para></listitem>
<listitem><para>
<filename>oe-pkgdata-util list-pkg-files&nbsp;</filename><replaceable>package</replaceable><filename>&nbsp;...</filename>:
Lists the files and directories contained in the given
packages.
<note>
<para>
A different way to view the contents of a package is
to look at the
<filename>${</filename><link linkend='var-WORKDIR'><filename>WORKDIR</filename></link><filename>}/packages-split</filename>
directory of the recipe that generates the
package.
This directory is created by the
<link linkend='ref-tasks-package'><filename>do_package</filename></link>
task and has one subdirectory for each package the
recipe generates, which contains the files stored in
that package.</para>
<para>
If you want to inspect the
<filename>${WORKDIR}/packages-split</filename>
directory, make sure that
<link linkend='ref-classes-rm-work'><filename>rm_work</filename></link>
is not enabled when you build the recipe.
</para>
</note>
</para></listitem>
<listitem><para>
<filename>oe-pkgdata-util find-path&nbsp;</filename><replaceable>path</replaceable><filename>&nbsp;...</filename>:
Lists the names of the packages that contain the given
paths.
For example, the following tells us that
<filename>/usr/share/man/man1/make.1</filename>
is contained in the <filename>make-doc</filename>
package:
<literallayout class='monospaced'>
$ oe-pkgdata-util find-path /usr/share/man/man1/make.1
make-doc: /usr/share/man/man1/make.1
</literallayout>
</para></listitem>
<listitem><para>
<filename>oe-pkgdata-util lookup-recipe&nbsp;</filename><replaceable>package</replaceable><filename>&nbsp;...</filename>:
Lists the name of the recipes that
produce the given packages.
</para></listitem>
</itemizedlist>
</para>
<para>
For more information on the <filename>oe-pkgdata-util</filename>
command, use the help facility:
<literallayout class='monospaced'>
$ oe-pkgdata-util &dash;&dash;help
$ oe-pkgdata-util <replaceable>subcommand</replaceable> --help
</literallayout>
</para>
</section>
<section id='usingpoky-viewing-dependencies-between-recipes-and-tasks'>
<title>Viewing Dependencies Between Recipes and Tasks</title>
<para>
Sometimes it can be hard to see why BitBake wants to build other
recipes before the one you have specified.
Dependency information can help you understand why a recipe is
built.
</para>
<para>
To generate dependency information for a recipe, run the following
command:
<literallayout class='monospaced'>
$ bitbake -g <replaceable>recipename</replaceable>
</literallayout>
This command writes the following files in the current directory:
<itemizedlist>
<listitem><para>
<filename>pn-buildlist</filename>: A list of
recipes/targets involved in building
<replaceable>recipename</replaceable>.
"Involved" here means that at least one task from the
recipe needs to run when building
<replaceable>recipename</replaceable> from scratch.
Targets that are in
<link linkend='var-ASSUME_PROVIDED'><filename>ASSUME_PROVIDED</filename></link>
are not listed.
</para></listitem>
<listitem><para>
<filename>task-depends.dot</filename>: A graph showing
dependencies between tasks.
</para></listitem>
</itemizedlist>
</para>
<para>
The graphs are in
<ulink url='https://en.wikipedia.org/wiki/DOT_%28graph_description_language%29'>DOT</ulink>
format and can be converted to images (e.g. using the
<filename>dot</filename> tool from
<ulink url='http://www.graphviz.org/'>Graphviz</ulink>).
<note><title>Notes</title>
<itemizedlist>
<listitem><para>
DOT files use a plain text format.
The graphs generated using the
<filename>bitbake -g</filename> command are often so
large as to be difficult to read without special
pruning (e.g. with Bitbake's
<filename>-I</filename> option) and processing.
Despite the form and size of the graphs, the
corresponding <filename>.dot</filename> files can still
be possible to read and provide useful information.
</para>
<para>As an example, the
<filename>task-depends.dot</filename> file contains
lines such as the following:
<literallayout class='monospaced'>
"libxslt.do_configure" -> "libxml2.do_populate_sysroot"
</literallayout>
The above example line reveals that the
<link linkend='ref-tasks-configure'><filename>do_configure</filename></link>
task in <filename>libxslt</filename> depends on the
<link linkend='ref-tasks-populate_sysroot'><filename>do_populate_sysroot</filename></link>
task in <filename>libxml2</filename>, which is a normal
<link linkend='var-DEPENDS'><filename>DEPENDS</filename></link>
dependency between the two recipes.
</para></listitem>
<listitem><para>
For an example of how <filename>.dot</filename> files
can be processed, see the
<filename>scripts/contrib/graph-tool</filename> Python
script, which finds and displays paths between graph
nodes.
</para></listitem>
</itemizedlist>
</note>
</para>
<para>
You can use a different method to view dependency information
by using the following command:
<literallayout class='monospaced'>
$ bitbake -g -u taskexp <replaceable>recipename</replaceable>
</literallayout>
This command displays a GUI window from which you can view
build-time and runtime dependencies for the recipes involved in
building <replaceable>recipename</replaceable>.
</para>
</section>
<section id='usingpoky-viewing-task-variable-dependencies'>
<title>Viewing Task Variable Dependencies</title>
<para>
As mentioned in the
"<ulink url='&YOCTO_DOCS_BB_URL;#checksums'>Checksums (Signatures)</ulink>"
section of the BitBake User Manual, BitBake tries to automatically
determine what variables a task depends on so that it can rerun
the task if any values of the variables change.
This determination is usually reliable.
However, if you do things like construct variable names at runtime,
then you might have to manually declare dependencies on those
variables using <filename>vardeps</filename> as described in the
"<ulink url='&YOCTO_DOCS_BB_URL;#variable-flags'>Variable Flags</ulink>"
section of the BitBake User Manual.
</para>
<para>
If you are unsure whether a variable dependency is being picked up
automatically for a given task, you can list the variable
dependencies BitBake has determined by doing the following:
<orderedlist>
<listitem><para>
Build the recipe containing the task:
<literallayout class='monospaced'>
$ bitbake <replaceable>recipename</replaceable>
</literallayout>
</para></listitem>
<listitem><para>
Inside the
<link linkend='var-STAMPS_DIR'><filename>STAMPS_DIR</filename></link>
directory, find the signature data
(<filename>sigdata</filename>) file that corresponds to the
task.
The <filename>sigdata</filename> files contain a pickled
Python database of all the metadata that went into creating
the input checksum for the task.
As an example, for the
<link linkend='ref-tasks-fetch'><filename>do_fetch</filename></link>
task of the <filename>db</filename> recipe, the
<filename>sigdata</filename> file might be found in the
following location:
<literallayout class='monospaced'>
${BUILDDIR}/tmp/stamps/i586-poky-linux/db/6.0.30-r1.do_fetch.sigdata.7c048c18222b16ff0bcee2000ef648b1
</literallayout>
For tasks that are accelerated through the shared state
(<ulink url='&YOCTO_DOCS_OVERVIEW_URL;#shared-state-cache'>sstate</ulink>)
cache, an additional <filename>siginfo</filename> file is
written into
<link linkend='var-SSTATE_DIR'><filename>SSTATE_DIR</filename></link>
along with the cached task output.
The <filename>siginfo</filename> files contain exactly the
same information as <filename>sigdata</filename> files.
</para></listitem>
<listitem><para>
Run <filename>bitbake-dumpsig</filename> on the
<filename>sigdata</filename> or
<filename>siginfo</filename> file.
Here is an example:
<literallayout class='monospaced'>
$ bitbake-dumpsig ${BUILDDIR}/tmp/stamps/i586-poky-linux/db/6.0.30-r1.do_fetch.sigdata.7c048c18222b16ff0bcee2000ef648b1
</literallayout>
In the output of the above command, you will find a line
like the following, which lists all the (inferred) variable
dependencies for the task.
This list also includes indirect dependencies from
variables depending on other variables, recursively.
<literallayout class='monospaced'>
Task dependencies: ['PV', 'SRCREV', 'SRC_URI', 'SRC_URI[md5sum]', 'SRC_URI[sha256sum]', 'base_do_fetch']
</literallayout>
<note>
Functions (e.g. <filename>base_do_fetch</filename>)
also count as variable dependencies.
These functions in turn depend on the variables they
reference.
</note>
The output of <filename>bitbake-dumpsig</filename> also includes
the value each variable had, a list of dependencies for each
variable, and
<ulink url='&YOCTO_DOCS_BB_URL;#var-BB_HASHBASE_WHITELIST'><filename>BB_HASHBASE_WHITELIST</filename></ulink>
information.
</para></listitem>
</orderedlist>
</para>
<para>
There is also a <filename>bitbake-diffsigs</filename> command for
comparing two <filename>siginfo</filename> or
<filename>sigdata</filename> files.
This command can be helpful when trying to figure out what changed
between two versions of a task.
If you call <filename>bitbake-diffsigs</filename> with just one
file, the command behaves like
<filename>bitbake-dumpsig</filename>.
</para>
<para>
You can also use BitBake to dump out the signature construction
information without executing tasks by using either of the
following BitBake command-line options:
<literallayout class='monospaced'>
&dash;&dash;dump-signatures=<replaceable>SIGNATURE_HANDLER</replaceable>
-S <replaceable>SIGNATURE_HANDLER</replaceable>
</literallayout>
<note>
Two common values for
<replaceable>SIGNATURE_HANDLER</replaceable> are "none" and
"printdiff", which dump only the signature or compare the
dumped signature with the cached one, respectively.
</note>
Using BitBake with either of these options causes BitBake to dump
out <filename>sigdata</filename> files in the
<filename>stamps</filename> directory for every task it would have
executed instead of building the specified target package.
</para>
</section>
<section id='usingpoky-debugging-taskrunning'>
<title>Running Specific Tasks</title>
<para>
Any given recipe consists of a set of tasks.
The standard BitBake behavior in most cases is:
<filename>do_fetch</filename>,
<filename>do_unpack</filename>,
<filename>do_patch</filename>, <filename>do_configure</filename>,
<filename>do_compile</filename>, <filename>do_install</filename>,
<filename>do_package</filename>,
<filename>do_package_write_*</filename>, and
<filename>do_build</filename>.
The default task is <filename>do_build</filename> and any tasks
on which it depends build first.
Some tasks, such as <filename>do_devshell</filename>, are not part
of the default build chain.
If you wish to run a task that is not part of the default build
chain, you can use the <filename>-c</filename> option in BitBake.
Here is an example:
<literallayout class='monospaced'>
$ bitbake matchbox-desktop -c devshell
</literallayout>
</para>
<para>
The <filename>-c</filename> option respects task dependencies,
which means that all other tasks (including tasks from other
recipes) that the specified task depends on will be run before the
task.
Even when you manually specify a task to run with
<filename>-c</filename>, BitBake will only run the task if it
considers it "out of date".
See the
"<ulink url='&YOCTO_DOCS_OVERVIEW_URL;#stamp-files-and-the-rerunning-of-tasks'>Stamp Files and the Rerunning of Tasks</ulink>"
section in the Yocto Project Overview Manual for how BitBake
determines whether a task is "out of date".
</para>
<para>
If you want to force an up-to-date task to be rerun (e.g.
because you made manual modifications to the recipe's
<link linkend='var-WORKDIR'><filename>WORKDIR</filename></link>
that you want to try out), then you can use the
<filename>-f</filename> option.
<note>
The reason <filename>-f</filename> is never required when
running the
<link linkend='ref-tasks-devshell'><filename>do_devshell</filename></link>
task is because the
<filename>[</filename><ulink url='&YOCTO_DOCS_BB_URL;#variable-flags'><filename>nostamp</filename></ulink><filename>]</filename>
variable flag is already set for the task.
</note>
The following example shows one way you can use the
<filename>-f</filename> option:
<literallayout class='monospaced'>
$ bitbake matchbox-desktop
.
.
make some changes to the source code in the work directory
.
.
$ bitbake matchbox-desktop -c compile -f
$ bitbake matchbox-desktop
</literallayout>
</para>
<para>
This sequence first builds and then recompiles
<filename>matchbox-desktop</filename>.
The last command reruns all tasks (basically the packaging tasks)
after the compile.
BitBake recognizes that the <filename>do_compile</filename>
task was rerun and therefore understands that the other tasks
also need to be run again.
</para>
<para>
Another, shorter way to rerun a task and all
<link linkend='normal-recipe-build-tasks'>normal recipe build tasks</link>
that depend on it is to use the <filename>-C</filename>
option.
<note>
This option is upper-cased and is separate from the
<filename>-c</filename> option, which is lower-cased.
</note>
Using this option invalidates the given task and then runs the
<link linkend='ref-tasks-build'><filename>do_build</filename></link>
task, which is the default task if no task is given, and the
tasks on which it depends.
You could replace the final two commands in the previous example
with the following single command:
<literallayout class='monospaced'>
$ bitbake matchbox-desktop -C compile
</literallayout>
Internally, the <filename>-f</filename> and
<filename>-C</filename> options work by tainting (modifying) the
input checksum of the specified task.
This tainting indirectly causes the task and its
dependent tasks to be rerun through the normal task dependency
mechanisms.
<note>
BitBake explicitly keeps track of which tasks have been
tainted in this fashion, and will print warnings such as the
following for builds involving such tasks:
<literallayout class='monospaced'>
WARNING: /home/ulf/poky/meta/recipes-sato/matchbox-desktop/matchbox-desktop_2.1.bb.do_compile is tainted from a forced run
</literallayout>
The purpose of the warning is to let you know that the work
directory and build output might not be in the clean state they
would be in for a "normal" build, depending on what actions
you took.
To get rid of such warnings, you can remove the work directory
and rebuild the recipe, as follows:
<literallayout class='monospaced'>
$ bitbake matchbox-desktop -c clean
$ bitbake matchbox-desktop
</literallayout>
</note>
</para>
<para>
You can view a list of tasks in a given package by running the
<filename>do_listtasks</filename> task as follows:
<literallayout class='monospaced'>
$ bitbake matchbox-desktop -c listtasks
</literallayout>
The results appear as output to the console and are also in the
file <filename>${WORKDIR}/temp/log.do_listtasks</filename>.
</para>
</section>
<section id='usingpoky-debugging-bitbake'>
<title>General BitBake Problems</title>
<para>
You can see debug output from BitBake by using the <filename>-D</filename> option.
The debug output gives more information about what BitBake
is doing and the reason behind it.
Each <filename>-D</filename> option you use increases the logging level.
The most common usage is <filename>-DDD</filename>.
</para>
<para>
The output from <filename>bitbake -DDD -v</filename> <replaceable>targetname</replaceable> can reveal why
BitBake chose a certain version of a package or why BitBake
picked a certain provider.
This command could also help you in a situation where you think BitBake did something
unexpected.
</para>
</section>
<section id='development-host-system-issues'>
<title>Development Host System Issues</title>
<para>
Sometimes issues on the host development system can cause your
build to fail.
Following are known, host-specific problems.
Be sure to always consult the
<ulink url='&YOCTO_RELEASE_NOTES;'>Release Notes</ulink>
for a look at all release-related issues.
<itemizedlist>
<listitem><para><emphasis><filename>glibc-initial</filename> fails to build</emphasis>:
If your development host system has the unpatched
<filename>GNU Make 3.82</filename>,
the
<link linkend='ref-tasks-install'><filename>do_install</filename></link>
task fails for <filename>glibc-initial</filename> during
the build.</para>
<para>Typically, every distribution that ships
<filename>GNU Make 3.82</filename> as
the default already has the patched version.
However, some distributions, such as Debian, have
<filename>GNU Make 3.82</filename> as an option, which
is unpatched.
You will see this error on these types of distributions.
Switch to <filename>GNU Make 3.81</filename> or patch
your <filename>make</filename> to solve the problem.
</para></listitem>
</itemizedlist>
</para>
</section>
<section id='usingpoky-debugging-buildfile'>
<title>Building with No Dependencies</title>
<para>
To build a specific recipe (<filename>.bb</filename> file),
you can use the following command form:
<literallayout class='monospaced'>
$ bitbake -b <replaceable>somepath</replaceable>/<replaceable>somerecipe</replaceable>.bb
</literallayout>
This command form does not check for dependencies.
Consequently, you should use it
only when you know existing dependencies have been met.
<note>
You can also specify fragments of the filename.
In this case, BitBake checks for a unique match.
</note>
</para>
</section>
<section id='recipe-logging-mechanisms'>
<title>Recipe Logging Mechanisms</title>
<para>
The Yocto Project provides several logging functions for producing
debugging output and reporting errors and warnings.
For Python functions, the following logging functions exist.
All of these functions log to
<filename>${T}/log.do_</filename><replaceable>task</replaceable>,
and can also log to standard output (stdout) with the right
settings:
<itemizedlist>
<listitem><para>
<filename>bb.plain(</filename><replaceable>msg</replaceable><filename>)</filename>:
Writes <replaceable>msg</replaceable> as is to the log while
also logging to stdout.
</para></listitem>
<listitem><para>
<filename>bb.note(</filename><replaceable>msg</replaceable><filename>)</filename>:
Writes "NOTE: <replaceable>msg</replaceable>" to the log.
Also logs to stdout if BitBake is called with "-v".
</para></listitem>
<listitem><para>
<filename>bb.debug(</filename><replaceable>level</replaceable><filename>,&nbsp;</filename><replaceable>msg</replaceable><filename>)</filename>:
Writes "DEBUG: <replaceable>msg</replaceable>" to the log.
Also logs to stdout if the log level is greater than or
equal to <replaceable>level</replaceable>.
See the
"<ulink url='&YOCTO_DOCS_BB_URL;#usage-and-syntax'>-D</ulink>"
option in the BitBake User Manual for more information.
</para></listitem>
<listitem><para>
<filename>bb.warn(</filename><replaceable>msg</replaceable><filename>)</filename>:
Writes "WARNING: <replaceable>msg</replaceable>" to the log
while also logging to stdout.
</para></listitem>
<listitem><para>
<filename>bb.error(</filename><replaceable>msg</replaceable><filename>)</filename>:
Writes "ERROR: <replaceable>msg</replaceable>" to the log
while also logging to stdout.
<note>
Calling this function does not cause the task to fail.
</note>
</para></listitem>
<listitem><para>
<filename>bb.fatal(</filename><replaceable>msg</replaceable><filename>)</filename>:
This logging function is similar to
<filename>bb.error(</filename><replaceable>msg</replaceable><filename>)</filename>
but also causes the calling task to fail.
<note>
<filename>bb.fatal()</filename> raises an exception,
which means you do not need to put a "return"
statement after the function.
</note>
</para></listitem>
</itemizedlist>
</para>
<para>
The same logging functions are also available in shell functions,
under the names
<filename>bbplain</filename>, <filename>bbnote</filename>,
<filename>bbdebug</filename>, <filename>bbwarn</filename>,
<filename>bberror</filename>, and <filename>bbfatal</filename>.
The
<link linkend='ref-classes-logging'><filename>logging</filename></link>
class implements these functions.
See that class in the
<filename>meta/classes</filename> folder of the
<link linkend='source-directory'>Source Directory</link>
for information.
</para>
<section id='logging-with-python'>
<title>Logging With Python</title>
<para>
When creating recipes using Python and inserting code that handles build logs,
keep in mind the goal is to have informative logs while keeping the console as
"silent" as possible.
Also, if you want status messages in the log, use the "debug" loglevel.
</para>
<para>
Following is an example written in Python.
The code handles logging for a function that determines the
number of tasks needed to be run.
See the
"<link linkend='ref-tasks-listtasks'><filename>do_listtasks</filename></link>"
section for additional information:
<literallayout class='monospaced'>
python do_listtasks() {
bb.debug(2, "Starting to figure out the task list")
if noteworthy_condition:
bb.note("There are 47 tasks to run")
bb.debug(2, "Got to point xyz")
if warning_trigger:
bb.warn("Detected warning_trigger, this might be a problem later.")
if recoverable_error:
bb.error("Hit recoverable_error, you really need to fix this!")
if fatal_error:
bb.fatal("fatal_error detected, unable to print the task list")
bb.plain("The tasks present are abc")
bb.debug(2, "Finished figuring out the tasklist")
}
</literallayout>
</para>
</section>
<section id='logging-with-bash'>
<title>Logging With Bash</title>
<para>
When creating recipes using Bash and inserting code that handles build
logs, you have the same goals - informative with minimal console output.
The syntax you use for recipes written in Bash is similar to that of
recipes written in Python described in the previous section.
</para>
<para>
Following is an example written in Bash.
The code logs the progress of the <filename>do_my_function</filename> function.
<literallayout class='monospaced'>
do_my_function() {
bbdebug 2 "Running do_my_function"
if [ exceptional_condition ]; then
bbnote "Hit exceptional_condition"
fi
bbdebug 2 "Got to point xyz"
if [ warning_trigger ]; then
bbwarn "Detected warning_trigger, this might cause a problem later."
fi
if [ recoverable_error ]; then
bberror "Hit recoverable_error, correcting"
fi
if [ fatal_error ]; then
bbfatal "fatal_error detected"
fi
bbdebug 2 "Completed do_my_function"
}
</literallayout>
</para>
</section>
</section>
<section id='usingpoky-debugging-others'>
<title>Other Tips</title>
<para>
Here are some other tips that you might find useful:
<itemizedlist>
<listitem><para>
When adding new packages, it is worth watching for
undesirable items making their way into compiler command
lines.
For example, you do not want references to local system
files like
<filename>/usr/lib/</filename> or
<filename>/usr/include/</filename>.
</para></listitem>
<listitem><para>
If you want to remove the <filename>psplash</filename>
boot splashscreen,
add <filename>psplash=false</filename> to the kernel
command line.
Doing so prevents <filename>psplash</filename> from loading
and thus allows you to see the console.
It is also possible to switch out of the splashscreen by
switching the virtual console (e.g. Fn+Left or Fn+Right
on a Zaurus).
</para></listitem>
<listitem><para>
Removing
<link linkend='var-TMPDIR'><filename>TMPDIR</filename></link>
(usually <filename>tmp/</filename>, within the
<link linkend='build-directory'>Build Directory</link>)
can often fix temporary build issues.
Removing <filename>TMPDIR</filename> is usually a
relatively cheap operation, because task output will be
cached in
<link linkend='var-SSTATE_DIR'><filename>SSTATE_DIR</filename></link>
(usually <filename>sstate-cache/</filename>, which is
also in the Build Directory).
<note>
Removing <filename>TMPDIR</filename> might be a
workaround rather than a fix.
Consequently, trying to determine the underlying cause
of an issue before removing the directory is a good
idea.
</note>
</para></listitem>
<listitem><para>
Understanding how a feature is used in practice within
existing recipes can be very helpful.
It is recommended that you configure some method that
allows you to quickly search through files.</para>
<para>Using GNU Grep, you can use the following shell
function to recursively search through common
recipe-related files, skipping binary files,
<filename>.git</filename> directories, and the
Build Directory (assuming its name starts with
"build"):
<literallayout class='monospaced'>
g() {
grep -Ir \
--exclude-dir=.git \
--exclude-dir='build*' \
--include='*.bb*' \
--include='*.inc*' \
--include='*.conf*' \
--include='*.py*' \
"$@"
}
</literallayout>
Following are some usage examples:
<literallayout class='monospaced'>
$ g FOO # Search recursively for "FOO"
$ g -i foo # Search recursively for "foo", ignoring case
$ g -w FOO # Search recursively for "FOO" as a word, ignoring e.g. "FOOBAR"
</literallayout>
If figuring out how some feature works requires a lot of
searching, it might indicate that the documentation should
be extended or improved.
In such cases, consider filing a documentation bug using
the Yocto Project implementation of
<ulink url='https://bugzilla.yoctoproject.org/'>Bugzilla</ulink>.
For general information on how to submit a bug against
the Yocto Project, see the Yocto Project Bugzilla
<ulink url='&YOCTO_WIKI_URL;/wiki/Bugzilla_Configuration_and_Bug_Tracking'>wiki page</ulink>"
or the
<ulink url='&YOCTO_DOCS_DEV_URL;#submitting-a-defect-against-the-yocto-project'>Submitting a Defect Against the Yocto Project</ulink>"
section, which is in the Yocto Project Development Tasks
Manual.
<note>
The manuals might not be the right place to document
variables that are purely internal and have a limited
scope (e.g. internal variables used to implement a
single <filename>.bbclass</filename> file).
</note>
</para></listitem>
</itemizedlist>
</para>
</section>
</section>
<section id='ref-quick-emulator-qemu'> <section id='ref-quick-emulator-qemu'>
<title>Quick EMUlator (QEMU)</title> <title>Quick EMUlator (QEMU)</title>