The image_ipkg class is used to generate filesystem images containing a root filesystem, as generated by the , for use on the target device. This could be a jffs2 image which is to be written directly into the flash on the target device for example. In addition this class also configures the ipkg feeds (where to get updates from) and is able to generate multiple different image types. Summary of the actions performed by the image_ipkg class: Inherits the in order to bring in the functionality required to generate a root filesystem image. The root filesystem image is generate from a set of ipkg packages, and then the required images are generated using the contents of the root filesystem; Sets BUILD_ALL_DEPS = "1" to force the dependency system to build all packages that are listed in the RDEPENDS and/or RRECOMENDS of the packages to be installed; Determines the name of the image device tables or table (IMAGE_DEVICE_TABLES/IMAGE_DEVICE_TABLE) which will be used to describe the device nodes to create in /dev directory in the root filesystem; Erases the contents of any existing root filesystem image, ${IMAGE_ROOTFS}; If devfs is not being used then the /dev directory, ${IMAGE_ROOTFS}/dev, will be created and then populated with the device nodes described by the image device table or tables (using "makedevs -r ${IMAGE_ROOTFS} -D <table>" for each device table); Calls into to install all of the required packages into the root filesystem; Configures the ipkg feed information in the root filesystem for the FEED_URIS; Runs any image pre-processing commands as specified via ${IMAGE_PREPROCESS_COMMAND}; Calls bbimage on the root filesystem for each required image type, as specified via ${IMAGE_FSTYPES}, to generate the actual filesystem images; Runs any image post-processing commands, as specified via ${IMAGE_POSTPROCESS_COMMAND}. The following variables may be used to control some of the behaviour of this class (remember we use to build the filesystem image, so look at the variables defined by that class as well): USE_DEVFS Indicates if the image will be using devfs, the device filesystem, or not. If devfs is being used then no /dev directory will be required in the image. Set to "1" to indicate that devfs is being used. Note that devfs has been removed from the Linux kernel in the 2.6 series and most platforms are moving towards the use of udev as a replacement for devfs. Default: "0" IMAGE_DEVICE_TABLES Specifies one, or more, files containing a list of the device nodes that should be created in the /dev directory of the image. Each file is searched for via the ${BBPATH} and therefore can be specified as a file relative to the top of the build. Device files are processed in the specified order. NOTE: If IMAGE_DEVICE_TABLE is set then this variable is ignored. Example: IMAGE_DEVICE_TABLES = "files/device_table-minimal.txt files/device_table_add-sci.txt device_table_add-sm.txt" Default: "files/device_table-minimal.txt" IMAGE_DEVICE_TABLE Specifies the file that lists the device nodes that should be created in the /dev directory of the image. This needs to be an absolute filename and so should be specified relative to ${BBPATH}. Only a single device table is supported. Use IMAGE_DEVICE_TABLES instead if you want to use multiple device tables. Default: "" IMAGE_PREPROCESS_COMMAND Additional commands to run prior to processing the image. Note that these command run within the same instance as the rest of this class. Default: "" IMAGE_POSTPROCESS_COMMAND Additional commands to run after processing the image. Note that these command run within the same instance as the rest of this class. Default: "" IMAGE_FSTYPES Specifies the type of image files to create. The supported image types, and details on modifying existing types and on creating new types, are described in the section. This variable is set to a space seperated list of image types to generate. Example: "jffs2 tar.gz" Default: "jffs2" FEED_URIS The name of the feeds to be configured in the image by default. Each entry consists of the feed name, followed by two pound signs and then followed by the actual feed URI. Example: FEED_URIS = "example##http://dist.example.com/ipkg-titan-glibc/" Default: ""

Special nodes, such as /dev nodes, and files with special permissions, such as suid files, are handled via the system. This means that when you view the contents of the root filesystem these device appear to be created incorrectly: The IMAGE_PREPROCESS_COMMAND and IMAGE_POSTPROCESS_COMMAND variables will be processed within the same instance as the rest of the rest of this class.

There are two variables that can be defined for creating device nodes. The new method supports multiple device node tables and supports searching for these tables via the ${BBPATH} so that relative file names may be used. The following example from machine/titan.conf shows the use of multiple device tables: # Add the SCI devices to minimal /dev IMAGE_DEVICE_TABLES = "files/device_table-minimal.txt files/device_table_add-sci.txt device_table_add-sm.txt" It uses the standard minimal device tables but adds some additional items which are not normally needed: files/device_table-minimal.txt This is the standard minimal set of device nodes. files/device_table_add-sci.txt This contains details for creating the /dev/SC{0,1,2} nodes which are required for the SH processors on board SCI and SCIF serial ports. On the titan hardware the serial console is provided via one of these ports and so we require the device node to be present. device_table_add-sm.txt This contains details for creating the /dev/sm0 and /dev/sm0p{0,1,2} devices nodes for the block driver, and the associated partitions, that are used to manage the on board flash on the titan hardware. Prior to support for multiple device tables this would have required the creation of a titan specific device table.

The type of filesystem images to create are specified via the IMAGE_FSTYPES variable. A full description of the available image types, options of the images and details on creating new image types is provided in the section.

Package feeds are used by the ipkg command to determine where to retrieve updates and new packages from. Multiple feeds are supported. Each feed provides a feed name and the URL which will contain the packages. The following example shows the addition of two feeds, one called base and one called updates: FEED_URIS += " \ base##http://oe.example.com/releases/${DISTRO_VERSION}/feed/base \ updates##http://oe.example.com/releases/${DISTRO_VERSION}/feed/updates"