# Build process - Tasks

This describes all tasks that are executed when building a recipe or distribution.

## `do_package_write_<pkgtype>`


For all packages selected with `PACKAGE_CLASSES`, packages are downloaded into `DL_DIR`

Default: `poky/build/tmp/deploy/<pkgtype>/<arch>/`

- pkgtype: rpm, ipk, deb
- arch: genericx86, ...

Those packages can also be built from sources with the folowing commands.

## `do_fetch` & `do_unpack`


Downloads and extracts the package sources.

```text
poky/build/tmp/work/
└── <PACKAGE_ARCH>-poky-linux or <MACHINE>-poky-linux
		└── <PACKAGE_NAME>
				└── <RECIPE_VERSION>-<RECIPE_REVISION> : The package is built from here
						└── <PACKAGE_NAME>-<RECIPE_VERSION> : Package sources
```

## `do_patch`


Apply some yocto-related patches to package source
The patches are listed in `SRC_URI` in the recipe file

## `do_configure`, `do_compile`, `do_install`



In most cases:
- `do_configure`: `./configure`
- `do_compile`: `make`
- `do_install`: `make install`

The work directory is:
```text
poky/build/tmp/work/
└── <PACKAGE_ARCH>-poky-linux or <MACHINE>-poky-linux
		└── <PACKAGE_NAME>
				└── <RECIPE_VERSION>-<RECIPE_REVISION>
```

From the work directory:
- `<PACKAGE_NAME>-<RECIPE_VERSION>`: Built files
- `image` : installed files (eg `./configure --prefix`)


## `do_package` & `do_packagedata`


`do_package` analyses the `image` dir:
- splits out debugging symbols
- checks shared library dependencies
- looks at package relationships

`do_packagedata` creates the package metadata file.

From working dir:
- `package`: The destination directory for packages before they are split
- `pkgdata`: A temporary work area used by the do_package task
- `packages-split`: The parent directory for packages after they have been split

These folders are used by `do_package_write_*` and generated packages are put into the package feed area (`poky/build/tmp/deploy/<pkgtype>/a<rch>/`)

## `do_rootfs`


Unpacks the packages from the package feed area (`poky/build/tmp/deploy/<pkgtype>/<arch>/`) to build the root filesystem, depending on the configuration :

- `IMAGE_INSTALL`: Which base package to install
- `PACKAGE_EXCLUDE`: Which packages to not install
- `IMAGE_FEATURES`: Which features to install. Features maps to specific packages to be installed.
- `PACKAGE_CLASSES`: Package type to use (deb, ipk, tar, ...)
- `IMAGE_LINGUAS`: Languages to install