.. SPDX-License-Identifier: CC-BY-SA-2.0-UK
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Yocto Project Profiling and Tracing Manual
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Introduction
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============
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Yocto bundles a number of tracing and profiling tools - this 'HOWTO'
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describes their basic usage and shows by example how to make use of them
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to examine application and system behavior.
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The tools presented are for the most part completely open-ended and have
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quite good and/or extensive documentation of their own which can be used
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to solve just about any problem you might come across in Linux. Each
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section that describes a particular tool has links to that tool's
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documentation and website.
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The purpose of this 'HOWTO' is to present a set of common and generally
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useful tracing and profiling idioms along with their application (as
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appropriate) to each tool, in the context of a general-purpose
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'drill-down' methodology that can be applied to solving a large number
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(90%?) of problems. For help with more advanced usages and problems,
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please see the documentation and/or websites listed for each tool.
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The final section of this 'HOWTO' is a collection of real-world examples
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which we'll be continually adding to as we solve more problems using the
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tools - feel free to add your own examples to the list!
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General Setup
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=============
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Most of the tools are available only in 'sdk' images or in images built
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after adding 'tools-profile' to your local.conf. So, in order to be able
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to access all of the tools described here, please first build and boot
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an 'sdk' image e.g. ::
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$ bitbake core-image-sato-sdk
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or alternatively by adding 'tools-profile' to the EXTRA_IMAGE_FEATURES line in
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your local.conf::
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EXTRA_IMAGE_FEATURES = "debug-tweaks tools-profile"
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If you use the 'tools-profile' method, you don't need to build an sdk image -
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the tracing and profiling tools will be included in non-sdk images as well e.g.::
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$ bitbake core-image-sato
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.. note::
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By default, the Yocto build system strips symbols from the binaries
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it packages, which makes it difficult to use some of the tools.
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You can prevent that by setting the
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:term:`INHIBIT_PACKAGE_STRIP`
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variable to "1" in your ``local.conf`` when you build the image::
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INHIBIT_PACKAGE_STRIP = "1"
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The above setting will noticeably increase the size of your image.
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If you've already built a stripped image, you can generate debug
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packages (xxx-dbg) which you can manually install as needed.
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To generate debug info for packages, you can add dbg-pkgs to
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EXTRA_IMAGE_FEATURES in local.conf. For example::
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EXTRA_IMAGE_FEATURES = "debug-tweaks tools-profile dbg-pkgs"
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Additionally, in order to generate the right type of debuginfo, we also need to
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set :term:`PACKAGE_DEBUG_SPLIT_STYLE` in the ``local.conf`` file::
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PACKAGE_DEBUG_SPLIT_STYLE = 'debug-file-directory'
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