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Diffstat (limited to 'poky/documentation/overview-manual/concepts.rst')
| -rw-r--r-- | poky/documentation/overview-manual/concepts.rst | 73 |
1 files changed, 34 insertions, 39 deletions
diff --git a/poky/documentation/overview-manual/concepts.rst b/poky/documentation/overview-manual/concepts.rst index 2e3f1af44..e5bdcdad2 100644 --- a/poky/documentation/overview-manual/concepts.rst +++ b/poky/documentation/overview-manual/concepts.rst @@ -139,7 +139,7 @@ hardware-specific configurations allows you to share other metadata by using a different layer where that metadata might be common across several pieces of hardware. -Many layers exist that work in the Yocto Project development environment. The +There are many layers working in the Yocto Project development environment. The :yocto_home:`Yocto Project Curated Layer Index </software-overview/layers/>` and :oe_layerindex:`OpenEmbedded Layer Index <>` both contain layers from which you can use or leverage. @@ -370,7 +370,7 @@ BitBake's global behavior. This section takes a closer look at the layers the build system uses to further control the build. These layers provide Metadata for the software, machine, and policies. -In general, three types of layer input exists. You can see them below +In general, there are three types of layer input. You can see them below the "User Configuration" box in the `general workflow figure <overview-manual/concepts:openembedded build system concepts>`: @@ -427,8 +427,8 @@ Repositories <>` also shows layers categorized under "Yocto Metadata Layers." .. note:: - Layers exist in the Yocto Project Source Repositories that cannot be - found in the OpenEmbedded Layer Index. These layers are either + There are layers in the Yocto Project Source Repositories that cannot be + found in the OpenEmbedded Layer Index. Such layers are either deprecated or experimental in nature. BitBake uses the ``conf/bblayers.conf`` file, which is part of the user @@ -489,7 +489,7 @@ the machine (``conf/machine/machine.conf``) and, of course, the layer The remainder of the layer is dedicated to specific recipes by function: ``recipes-bsp``, ``recipes-core``, ``recipes-graphics``, -``recipes-kernel``, and so forth. Metadata can exist for multiple +``recipes-kernel``, and so forth. There can be metadata for multiple formfactors, graphics support systems, and so forth. .. note:: @@ -528,9 +528,7 @@ project that is more dynamic or experimental in nature, a project might keep source files in a repository controlled by a Source Control Manager (SCM) such as Git. Pulling source from a repository allows you to control the point in the repository (the revision) from which you want -to build software. Finally, a combination of the two might exist, which -would give the consumer a choice when deciding where to get source -files. +to build software. A combination of the two is also possible. BitBake uses the :term:`SRC_URI` variable to point to source files regardless of their location. Each @@ -609,7 +607,7 @@ the specific revision from which to build. Source Mirror(s) ~~~~~~~~~~~~~~~~ -Two kinds of mirrors exist: pre-mirrors and regular mirrors. The +There are two kinds of mirrors: pre-mirrors and regular mirrors. The :term:`PREMIRRORS` and :term:`MIRRORS` variables point to these, respectively. BitBake checks pre-mirrors before looking upstream @@ -667,8 +665,8 @@ package files are kept: variables are used, respectively. - :term:`PACKAGE_ARCH`: Defines - architecture-specific sub-folders. For example, packages could exist - for the i586 or qemux86 architectures. + architecture-specific sub-folders. For example, packages could be + available for the i586 or qemux86 architectures. BitBake uses the :ref:`do_package_write_* <ref-tasks-package_write_deb>` @@ -681,8 +679,8 @@ and ":ref:`ref-tasks-package_write_tar`" sections in the Yocto Project Reference Manual for additional information. As an example, consider a scenario where an IPK packaging -manager is being used and package architecture support for both i586 and -qemux86 exist. Packages for the i586 architecture are placed in +manager is being used and there is package architecture support for both +i586 and qemux86. Packages for the i586 architecture are placed in ``build/tmp/deploy/ipk/i586``, while packages for the qemux86 architecture are placed in ``build/tmp/deploy/ipk/qemux86``. @@ -698,7 +696,7 @@ closer look at each of those areas. .. note:: - Separate documentation exists for the BitBake tool. See the + Documentation for the BitBake tool is available separately. See the BitBake User Manual for reference material on BitBake. @@ -783,12 +781,10 @@ Build Directory's hierarchy: .. note:: - In the previous figure, notice that two sample hierarchies exist: one - based on package architecture (i.e. - PACKAGE_ARCH - ) and one based on a machine (i.e. - MACHINE - ). The underlying structures are identical. The differentiator being + In the previous figure, notice that there are two sample hierarchies: + one based on package architecture (i.e. :term:`PACKAGE_ARCH`) + and one based on a machine (i.e. :term:`MACHINE`). + The underlying structures are identical. The differentiator being what the OpenEmbedded build system is using as a build target (e.g. general architecture, a build host, an SDK, or a specific machine). @@ -963,8 +959,7 @@ that part of the build process. .. note:: - Support for creating feeds directly from the - deploy/\* + Support for creating feeds directly from the ``deploy/*`` directories does not exist. Creating such feeds usually requires some kind of feed maintenance mechanism that would upload the new packages into an official package feed (e.g. the Ångström distribution). This @@ -1156,9 +1151,9 @@ checksum <overview-manual/concepts:checksums (signatures)>`. OpenEmbedded. To determine if a task needs to be rerun, BitBake checks if a stamp file -with a matching input checksum exists for the task. If such a stamp file -exists, the task's output is assumed to exist and still be valid. If the -file does not exist, the task is rerun. +with a matching input checksum exists for the task. In this case, +the task's output is assumed to exist and still be valid. Otherwise, +the task is rerun. .. note:: @@ -1234,14 +1229,14 @@ to run any of the ``do_fetch``, ``do_unpack``, ``do_patch``, It becomes more complicated if everything can come from an sstate cache because some objects are simply not required at all. For example, you do -not need a compiler or native tools, such as quilt, if nothing exists to -compile or patch. If the ``do_package_write_*`` packages are available +not need a compiler or native tools, such as quilt, if there isn't anything +to compile or patch. If the ``do_package_write_*`` packages are available from sstate, BitBake does not need the ``do_package`` task data. To handle all these complexities, BitBake runs in two phases. The first is the "setscene" stage. During this stage, BitBake first checks the sstate cache for any targets it is planning to build. BitBake does a -fast check to see if the object exists rather than a complete download. +fast check to see if the object exists rather than doing a complete download. If nothing exists, the second phase, which is the setscene stage, completes and the main build proceeds. @@ -1366,9 +1361,9 @@ can initialize the environment before using the tools. All the output files for an SDK are written to the ``deploy/sdk`` folder inside the :term:`Build Directory` as -shown in the previous figure. Depending on the type of SDK, several -variables exist that help configure these files. The following list -shows the variables associated with an extensible SDK: +shown in the previous figure. Depending on the type of SDK, there are +several variables to configure these files. Here are the variables +associated with an extensible SDK: - :term:`DEPLOY_DIR`: Points to the ``deploy`` directory. @@ -1577,8 +1572,8 @@ Shared State Cache By design, the OpenEmbedded build system builds everything from scratch unless :term:`BitBake` can determine that parts do not need to be rebuilt. Fundamentally, building from -scratch is attractive as it means all parts are built fresh and no -possibility of stale data exists that can cause problems. When +scratch is attractive as it means all parts are built fresh and there is +no possibility of stale data that can cause problems. When developers hit problems, they typically default back to building from scratch so they have a know state from the start. @@ -1617,7 +1612,7 @@ them if they are deemed to be valid. - The build system does not maintain :term:`PR` information as part of - the shared state packages. Consequently, considerations exist that + the shared state packages. Consequently, there are considerations that affect maintaining shared state feeds. For information on how the build system works with packages and can track incrementing ``PR`` information, see the ":ref:`dev-manual/common-tasks:automatically incrementing a package version number`" @@ -1687,7 +1682,7 @@ used to prune the "run" scripts down to the minimum set, thereby alleviating this problem and making the "run" scripts much more readable as a bonus. -So far, solutions for shell scripts exist. What about Python tasks? The +So far, there are solutions for shell scripts. What about Python tasks? The same approach applies even though these tasks are more difficult. The process needs to figure out what variables a Python function accesses and what functions it calls. Again, the incremental build solution @@ -1695,7 +1690,7 @@ contains code that first figures out the variable and function dependencies, and then creates a checksum for the data used as the input to the task. -Like the ``WORKDIR`` case, situations exist where dependencies should be +Like the ``WORKDIR`` case, there can be situations where dependencies should be ignored. For these situations, you can instruct the build process to ignore a dependency by using a line like the following:: @@ -1732,7 +1727,7 @@ to add is a policy decision. However, the effect is to generate a master checksum that combines the basehash and the hashes of the task's dependencies. -At the code level, a variety of ways exist by which both the basehash +At the code level, there are multiple ways by which both the basehash and the dependent task hashes can be influenced. Within the BitBake configuration file, you can give BitBake some extra information to help it construct the basehash. The following statement effectively results @@ -1961,8 +1956,8 @@ Automatically Added Runtime Dependencies The OpenEmbedded build system automatically adds common types of runtime dependencies between packages, which means that you do not need to explicitly declare the packages using -:term:`RDEPENDS`. Three automatic -mechanisms exist (``shlibdeps``, ``pcdeps``, and ``depchains``) that +:term:`RDEPENDS`. There are three automatic +mechanisms (``shlibdeps``, ``pcdeps``, and ``depchains``) that handle shared libraries, package configuration (pkg-config) modules, and ``-dev`` and ``-dbg`` packages, respectively. For other types of runtime dependencies, you must manually declare the dependencies. |