ARMImageSelection

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As we develop new ideas for features in Ubuntu, it's important to be able to communicate them clearly. This serves the purpose of making it clear what the feature is about, and allowing people to evolve an implementation strategy for it.

Publishing this content gives our community a chance to participate in the discussion and design of a feature, and increases the chance that community members will feel confident enough to start work on the implementation of the feature.

A good specification also allows community members who were not physically present at meetings discussing a topic to participate in the implementation of the spec.

Bottom line: the better your spec, the better the chances that your ideas will be clearly understood by the review team.
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  * Bob is the maintainer for the boot process for Ubuntu. In the Dapper cycle, he would like to work on getting the boot time down to two seconds from boot manager to GDM screen. He creates an entry for the specification in Launchpad, proposes it for the UBZ sprint, and starts writing out a braindump of it in the Ubuntu wiki. Magnus, who is in charge of UBZ scheduling, thinks it sounds fishy but approves it to make sure that the change is discussed and documented properly. He marks it as priority Medium because he isn't sure Bob will have time free for implementing it during Dapper.

  * Pedro works on Malone, in Launchpad. Before UBZ, he remembers that the dependency handling in the bug tracker is really not optimal. He writes out a Summary and Rationale in a Launchpad wiki page, registers it as a specification in Launchpad, and suggests it for UBZ. Monica, Launchpad manageress, thinks that this is really not the time to be talking about it and rejects the application for UBZ. He then indicates it for the next conference, UBB, and marks its priority is Low.

  * Jason is an Ubuntu and Rosetta user. He has noticed that changes made to translations are making their way into language packs but not to the upstream versions, and adds a specification that describes a way for getting upstream to use language packs. Monica also has a plan for this but hadn't described it in a spec, so she adds it to the UBZ spec list, and adds Carlos, Rosetta maintainer, as drafter for it.
  
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This specification covers feature specifications for Ubuntu and Launchpad. It is not meant as a more general specification format.
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A specification should be built with the following considerations:

  * The person implementing it may not be the person writing it. It should be clear enough for someone to be able to read it and have a clear path towards implementing it. If it doesn't, it needs more detail.

  * That the use cases covered in the specification should be practical situations, not contrived issues.

  * Limitations and issues discovered during the creation of a specification should be clearly pointed out so that they can be dealt with explicitly.

  * If you don't know enough to be able to competently write a spec, you should either get help or research the problem further. Avoid spending time making up a solution: base yourself on your peers' opinions and prior work.

  * Specifications should be written in clear, concise and correct English. If you're not a native speaker, co-editing the spec with somebody who is might be a good idea.

Specific issues related to particular sections are described further below.
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The summary should not attempt to say '''why''' the spec is being defined, just '''what''' is being specified.
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This should be the description of '''why''' this spec is being defined.
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While not always required, but in many cases they bring much better clarity to the scope and scale of the specification than could be obtained by talking in abstract terms.
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Use cases are positive statements which (loosely) conform to a pattern like
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  * A person and their role
  * The objective they want to achieve
  * The steps they go through
  * The positive result
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Specifically, describing the current unsatisfactory state of affairs is not a use case; that belongs in the Rationale section.
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=== Implementation Plan ===

This section is usually broken down into subsections, such as the packages being affected, data and system migration where necessary, user interface requirements and pictures (photographs of drawings on paper work well).
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To implement a specification, the assignee should observe the use cases carefully, and follow the design specified. He should make note of places in which he has strayed from the design section, adding rationale describing why this happened. This is important so that next iterations of this specification (and new specifications that touch upon this subject) can use the specification as a reference.

The implementation is very dependent on the type of feature to be implemented. Refer to the team leader for further suggestions and guidance on this topic.
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The specification process requires experienced people to drive it. More documentation on the process should be produced.
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The drafting of a specification requires English skills and a very good understanding of the problem. It must also describe things to an extent that someone else could implement. This is a difficult set of conditions to ensure throughout all the specifications added.

There is a lot of difficulty in gardening obsolete, unwanted and abandoned specifications in the Wiki.
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We'll have a first public session on this on the first Monday in UBZ. = 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

Summary

This specification describes an informational discussion held at UDS Jaunty in Mountainview about the right selection for images for the armel architecture

Rationale

Use Cases

Scope

Design

Summary

Rationale

Scope and Use Cases

Use Cases

Implementation

Outstanding Issues

BoF agenda and discussion

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

Specs/ARMImageSelection (last edited 2009-01-20 23:01:40 by p5098ed03)