diskimage-builder/diskimage_builder/elements/dracut-ramdisk/README.rst

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dracut-ramdisk
==============
Build Dracut-based ramdisks

This is an alternative to the `ramdisk` element that uses
Dracut to provide the base system functionality instead of
Busybox.

For elements that need additional drivers in the ramdisk image,
a dracut-drivers.d feature is included that works in a similar
fashion to the binary-deps.d feature.  The element needing to
add drivers should create a dracut-drivers.d directory and
populate it with a single file listing all of the kernel modules
it needs added to the ramdisk.  Comments are not supported in this
file.  Note that these modules must be installed in the chroot first.

By default, the virtio, virtio_net, and virtio_blk modules are
included so that ramdisks are able to function properly in a
virtualized environment.
Create docs site containing element READMEs We currently do not have the ability to create a docs site which outlines all the elements. Change-Id: I77ccf61e0c4b1509b3e7ce9b8f15ea5ccfd50d9b 2015-02-07 10:30:02 +00:00			`==============`
			`dracut-ramdisk`
			`==============`
Enable dracut deploy ramdisks The element builds dracut from source on Ubuntu because the Ubuntu dracut package is broken and very old, so it can't be installed properly and causes a number of other issues that are fixed by using a newer version of Dracut. This initial version should work in virtualized environments. Further validation of its suitability for real baremetal deployments will need to be done in the future, but this should be sufficient to enable that work. Regarding Dracut specifically, in order to limit the changes needed in the existing scripts this element continues to use a cut down version of the /init script that we were building for the existing ramdisk. However, instead of running it as pid 0 it is run as a Dracut pre-mount hook. This allows Dracut to set up all of the hardware and system bits, while falling early enough in the Dracut sequence to complete the deployment before Dracut would try to boot off the hard disk. bp tripleo-juno-dracut-ramdisks Change-Id: I144c8993fe040169f440bd4f7a428fdbe3d745cf 2014-09-26 05:12:32 +00:00			`Build Dracut-based ramdisks`

			This is an alternative to the `ramdisk` element that uses
			`Dracut to provide the base system functionality instead of`
			`Busybox.`
Allow elements to add drivers to dracut It is reasonable that elements may need to include additional kernel modules in a dracut ramdisk. This is done with the --add-drivers option to dracut, but previously the value passed was hard-coded. This change allows an element to put a file containing its desired drivers in a dracut-drivers.d directory, and the list there will be added to the list of drivers added. This functions in essentially the same way as the binary-deps.d directory that already exists for including additional executables in a ramdisk. Change-Id: Ie892b908d36c175a469f7cde7dd803ad4b1942b6 2015-01-30 19:50:49 +00:00
			`For elements that need additional drivers in the ramdisk image,`
			`a dracut-drivers.d feature is included that works in a similar`
			`fashion to the binary-deps.d feature. The element needing to`
			`add drivers should create a dracut-drivers.d directory and`
			`populate it with a single file listing all of the kernel modules`
			`it needs added to the ramdisk. Comments are not supported in this`
			`file. Note that these modules must be installed in the chroot first.`

			`By default, the virtio, virtio_net, and virtio_blk modules are`
			`included so that ramdisks are able to function properly in a`
			`virtualized environment.`