• Launchpad Entry: selection-of-arm-images

• Created: Monday, 05 Jaunary 2009

• Contributors: Michael Casadevall, Steven Kowalik

• Packages affected: ubuntu-cd, debian-install, ubiquity

Summary

Unlike most architectures, just having a traditional based CD image for ARM based machines is of limited usefulness since a vast majority of these boards do not come with CD-ROMs standard, and often times requires installing via flashing or installation over a network. This specification covers the type of images we will generate, and the rational behind it, as well as any unique issues about said images.

Release Note

Ubuntu/ARM installation varies from typical installation on other platforms, oftentimes booting from a USB based device, a network device or flash memory without the possibility of easily using an installation CD. The problem is further compounded that no "generic" ARM kernel or bootloader exists, and oftentimes kernels must been tweaked for existing hardware to be usable.

Rationale

Creating of installation that is usable on various pieces of hardware is vital for the success of the ARM architecture port.

Use Cases

• Alice wants to install Ubuntu on her NAS, which only has a small flash chip, and a large external hardware. She downloads a debian-installer image over the network via the NAS's bootloader, and then uses that to do a full installation on her hardware. She can conduct the installation using d-i's SSH installation mode.
• Bob has an ARM based MID that he wants to run Ubuntu on which can be booted off USB flash devices. He wants the graphical ubiquity installer to install ubuntu-desktop

Assumptions

• We will have at least one d-i image (server), and one ubiquity image (ubuntu-desktop) TBD futher

Design

• Content of the images
  • We might want to provide kernel-less "generic" filesystem images (rootfs);
    • first because the kernel is usually stored separately, and second because there will be many ARM kernels (one per subplatform almost)
  • We might instead include all kernels in a "generic" image, but this would
    • be very big (20 MB per kernel x number of flavours)

TBD futher

Implementation

Images we must build

• Jaunty VFAT images w/o kernel
  • Live ubuntu-desktop
  • debian-installer ubuntu-server

Would be nice if we have community support

• Live UNR (Requires X11 GL support)
• Live {K|X}ubuntu images

Possible future images

• Live MID
• Small storage image that could fit in small flash, and does not need mass storage available

UI Changes

The standard ubiquity and d-i UIs shall be used; with possibly changing the ubiquity UI to be usable on small screen devices (separate specification).

Code Changes

ubuntu-cd will likely need to be modified to create the multi-kernel image should we decide to persue that route. d-i supports network installation, boot from flash, run install over SSH and network booting already.

We need a utility to insert a kernel into an already existing image. Oliver has volunteered to write this tool.

Migration

N/A - this demo only applies to new installations.

Test/Demo Plan

It's important that we are able to test new features, and demonstrate them to users. Use this section to describe a short plan that anybody can follow that demonstrates the feature is working. This can then be used during testing, and to show off after release. Please add an entry to http://testcases.qa.ubuntu.com/Coverage/NewFeatures for tracking test coverage.

This need not be added or completed until the specification is nearing beta.

Unresolved issues

• Is there a standard similar to El Torito for ISO, or Master Boot Record, or Multiboot specification?

  • If not, how do we have <device> boot from USB? requires feedback from vendors

BoF agenda and discussion

Original Gobby Document

ARM images

* Various ways to boot

• - From JTAG (not considered for this session, use case covered in a different session) - Using a bootloader
  • - From USB - From network (tftp, others?) - From disk or flash

* Various bootloaders

• - Uboot - Redboot - Others

* Content of the images

• - We might want to provide kernel-less "generic" filesystem images (rootfs);
  • first because the kernel is usually stored separately, and second because there will be many ARM kernels (one per subplatform almost)
  - We might instead include all kernels in a "generic" image, but this would
  • be very big (20 MB per kernel x number of flavours)

* Do we need d-i? Yes, e.g. installation over SSH for display-less devices

* Jaunty vfat images, kernel-less

• - live ubuntu-desktop - d-i ubuntu-server

* Possible images, if we get community support

• - live UNR (needs GL support) - live kubuntu - live xubuntu

* Future possible images

• - live MID - extremely small image which would fit in flash and wouldn't require mass
  • storage such as a SATA disk

Work Needed

* We need a tool to edit an image to add a kernel (ogra volunteering)

Unresolved Issues

* Is there a standard similar to El Torito for ISO, or Master Boot Record, or

• Multiboot specification?

  - If not, how do we have <device> boot from USB? requires feedback from

  • vendors

CategorySpec