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Diffstat (limited to 'poky/documentation/ref-manual/terms.rst')
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diff --git a/poky/documentation/ref-manual/terms.rst b/poky/documentation/ref-manual/terms.rst index ec447d35d2..4baef38cfd 100644 --- a/poky/documentation/ref-manual/terms.rst +++ b/poky/documentation/ref-manual/terms.rst @@ -123,6 +123,10 @@ universal, the list includes them just in case: tools, such as a required version of the GCC compiler to run the OpenEmbedded build system. + See the ":ref:`system-requirements-buildtools`" paragraph in the + Reference Manual for details about downloading or building an archive + of such tools. + :term:`buildtools-make` A variant of :term:`buildtools`, just providing the required version of ``make`` to run the OpenEmbedded build system. @@ -208,6 +212,48 @@ universal, the list includes them just in case: of the supported image types that the Yocto Project provides, see the ":ref:`ref-manual/images:Images`" chapter. + :term:`Initramfs` + An Initial RAM Filesystem (:term:`Initramfs`) is an optionally compressed + :wikipedia:`cpio <Cpio>` archive which is extracted + by the Linux kernel into RAM in a special :wikipedia:`tmpfs <Tmpfs>` + instance, used as the initial root filesystem. + + This is a replacement for the legacy init RAM disk ("initrd") + technique, booting on an emulated block device in RAM, but being less + efficient because of the overhead of going through a filesystem and + having to duplicate accessed file contents in the file cache in RAM, + as for any block device. + + .. note: + + As far as bootloaders are concerned, :term:`Initramfs` and "initrd" + images are still copied to RAM in the same way. That's why most + most bootloaders refer to :term:`Initramfs` images as "initrd" + or "init RAM disk". + + This kind of mechanism is typically used for two reasons: + + - For booting the same kernel binary on multiple systems requiring + different device drivers. The :term:`Initramfs` image is then customized + for each type of system, to include the specific kernel modules + necessary to access the final root filesystem. This technique + is used on all GNU / Linux distributions for desktops and servers. + + - For booting faster. As the root filesystem is extracted into RAM, + accessing the first user-space applications is very fast, compared + to having to initialize a block device, to access multiple blocks + from it, and to go through a filesystem having its own overhead. + For example, this allows to display a splashscreen very early, + and to later take care of mounting the final root filesystem and + loading less time-critical kernel drivers. + + This cpio archive can either be loaded to RAM by the bootloader, + or be included in the kernel binary. + + For information on creating and using an :term:`Initramfs`, see the + ":ref:`dev-manual/building:building an initial ram filesystem (Initramfs) image`" + section in the Yocto Project Development Tasks Manual. + :term:`Layer` A collection of related recipes. Layers allow you to consolidate related metadata to customize your build. Layers also isolate information used @@ -227,6 +273,12 @@ universal, the list includes them just in case: Layers`" section in the Yocto Project Board Support Packages (BSP) Developer's Guide. + :term:`LTS` + This term means "Long Term Support", and in the context of the Yocto + Project, it corresponds to selected stable releases for which bug and + security fixes are provided for at least two years. See + the :ref:`ref-long-term-support-releases` section for details. + :term:`Metadata` A key element of the Yocto Project is the Metadata that is used to construct a Linux distribution and is contained in the @@ -246,6 +298,12 @@ universal, the list includes them just in case: :yocto_git:`yocto-kernel-cache </yocto-kernel-cache>` Git repository. + :term:`Mixin` + A :term:`Mixin` layer is a layer which can be created by the community to + add a specific feature or support a new version of some package for an + :term:`LTS` release. See the :ref:`ref-long-term-support-releases` + section for details. + :term:`OpenEmbedded-Core (OE-Core)` OE-Core is metadata comprised of foundational recipes, classes, and associated files that are meant to |