Anaconda/Features/NoLoader

Get rid of anaconda's loader

Summary

Stop using our old, crufty, hard-to-maintain C-based custom initrd. Move everything out of loader and into dracut or anaconda proper.

Owner

• Will Woods

Current status

• Targeted release: Fedora 17
• Last updated: Nov. 4, 2011
• Percentage of completion: 50%

Detailed Description

Since 1999, anaconda has been divided into two parts:

• stage1, a.k.a. initrd.img: the blue and red text loader environment (no shell, no virtual terminals, just a custom startup binary written in C - statically linked until 2008)
• stage2, a.k.a. install.img: the full installer environment (for graphical or text installs), complete with Python interpreter and shells and stuff.

In olden days, loader did what its name says - it loaded the stage2 (full graphical) anaconda environment and did a couple other tasks required to reach that objective. Those other tasks include things like:

• Prompting for language and keyboard (if loader goes interactive for one of the other tasks)
• Bringing up the network (if required by one of the other tasks)
• Fetching kickstart files, product.img, and updates.img (if requested)
• Loading driver disks (if required)
• Running media check

Most of the time, all of these things are skipped or happen automatically. If you use a boot.iso, you will most likely never see anything besides a blue background and the "Loading anaconda..." message. This means it's a whole lot of code that is just special cases and receives less testing all the time. Further, it's a special environment: It's newt, it's C, it's old, and it's another layer of stuff getting execed between startup and anaconda.

We need to decide how many of these tasks anaconda still needs to do. For those that are still important, they need to move either into the initramfs (if it's something that needs to happen before anaconda can start) or into the main anaconda program - or some other tool that anaconda can run when we're in the full graphical environment. Everything else should go away.

This may mean we keep some sort of loader-like program, but it could be Python based and non-interactive.

Benefit to Fedora

• Maintainability!
  • Gobs of custom code will move into upstream dracut modules or nice neat Python modules.
  • New stuff added to dracut will automatically appear in the installer!
• Debuggability!
  • There's a shell available as soon as the installer boots
  • Every part of the anaconda startup process becomes much easier to modify, since it's all shell or python
• Flexibility!
  • Moving to dracut-based initramfs means that anaconda can mount anything that dracut can mount
    • preupgrade won't need need to cram files into /boot anymore!
• Consistency!
  • The installer boots up the same way as a normal system, and the same as the Live images

Scope

• dracut - port stuff from loader
  • TODO: detailed list here
• anaconda - port stuff from loader
  • TODO: detailed list here

Test Plan

The normal should suffice.

User Experience

TBD. Some notes:

• We may remove all the interactive bits, so a few things there used to be (crappy text-based) UI for will now be configured on the boot commandline and/or in the bootloader menu.
• Some of the anaconda boot options may change or become deprecated.
  • We will do our best to keep backwards compatibility - for a few releases.

Dependencies

TBD; currently none.

Contingency Plan

Leave the system as-is - one big combined image, with loader still setting up for anaconda.