Open Embedded

From eLinux.org
Revision as of 15:47, 24 September 2007 by Tim Bird (Talk | contribs) (Case Study 1: Add Leon Woestenberg experience)

Jump to: navigation, search

Table Of Contents:


Description

Open Embedded is the name of a project which seeks to provide embedded linux distributions, built from scratch.

Rationale

While the distribution used for most embedded systems has many custom elements, there are significant portions of the software on consumer electronics products which could be standardized and utilized from the same source.

Open Embedded may represent the closest thing there is to a de-facto standard embedded distribution of Linux.

Resources

Projects

http://www.openembedded.org/

Specifications

There are no CELF specifications related to Open Embedded.

Downloads

Patch

- [Patch for 2.6.xx is *here* (often, the Patch Archive)]

Utility programs

[other programs, user-space, test, etc. related to this technology]

How To Use

See the Open Embedded wiki, at: http://www.openembedded.org/cgi-bin/moin.cgi

How to validate

[put references to test plans, scripts, methods, etc. here]

Sample Results

Case Study 1

Leon Woestenberg wrote (in Sep, 2007):


I became an OE user when I found that OE automated a lot more than buildroot when I started adding packages. After that experience I decided to use OE at work.

At work we create firmware, which is read-only embedded software which the user cannot install to, or modify in any way (other than overwrite) for 24/7 99.999% availability applications. Also, no build dependency on target availability during build: No on-target post-install scripts, the final image must be fully host-created. That means, having full control of what happens, minimal cruft. Must build on a multiple of (modern) Linux hosts distro's.

Bottom-line: paranoid control freak approach

I am the OE evangelist, that is, had to persuade to have my co-workers see the benefits of using OE. That worked best when I showed them how I could solve a problem more quickly than they could with buildroot, or LFS. The problem often remains the steep learning curve, i.e. people do often have some Makefile/autoconf experience but not necessarely python/bitbake.

Bottom line: Show when OE works when the 'problem solving' leverage is highest.

How do we use OpenEmbedded:

  • We cannot afford to follow the org.oe.dev. head developments. The head is where fixes get fixed. Takes too much time away from the developers.
  • We cannot afford to follow head, but fix package versions. The OE framework (bitbake, variables, behaviour) changes too much.
  • We pick a fixed OE revision and stick with it during a project (could be 2 years).
  • I try to track OE head on several targets, to stay up-to-date when I need to start a new project.
  • Some of the packages have too much build and/or run-time dependencies. Yes, both.
  • We create a private overlay of minimal-configured packages and discard redundant dependencies, we keep it in CVS (yes, I know...)
  • We add our custom packages to our private overlay.
  • I bring some new packages or fixes upstream, only for head.
  • We do not use task-base approach, because it builds dependencies we

did not have before (a dependency regression).

  • We have to keep good track of bitbake version, OE revision, private

overlay revision and host distro version, and know-good-combos'. We need to be able fix a bug in the firmware in three years without any regression. Virtual machines help.

Bottom line:

  • OpenEmbedded works perfectly for our use, if we take very much care in the way we use it. We might not do things the OE-way, simply we may lack in-depth knowledge, or exposure to it.

Issues:

  • Dependencies. The standard OE config seems targetted towards small (handheld) computing devices, not necessarely with embedded software. Everything with an installer is non-embedded software, IMHO.
    • I would like to see a OE group focus on minimal dependency distro.

I would join such a group, but cannot do that alone.

  • Angstrom seems the de-facto distro OE is tested against, at least

upstream. Angstrom is excellent, but testing OE against Angstrom only drives OE away from the embedded domain IMHO.

    • Unbitrot (Refresh) a distro other than Angstrom, preferably a more

minimal one.

  • Documentation.
    • It's there, but you have to know what you are looking for. Most people don't know, or don't look.
  • I have yet to see a developer walk in with OE experience. Buildroot

knowledge is a big plus though.

The best thing I would envision (and I would propose as a OE vision), is that OE would be funded by the semiconductor and board manufacturers to support their silicon and boards, so that in 3 years, everyone of them could mention "Enabled by OpenEmbedded".

Case Study 2

Future Work/Action Items

Here is a list of things that could be worked on for this feature:

- 

I met with Phil Blundell and Tim Ansell at Linuxconf Australia and discussed some possible ways the forum might sponsor Open Embedded. Here are some ideas:

- create an installer, which automatically copes with weird distros
(I had problems getting OE installed, but then I use Mandrake)
  - it should validate that all required packages are installed,
  and if not present, install them
    - OE has a somewhat long list of pre-requisites
- sponsor a conference/retreat of the core OE developers
- do nightly builds (and testing?) of various full-distro recipes
- do improvements to bitbake to solve the memory/performance
problems.
  - need to identify if these are python issues (dependency graph
  memory consumption seems to be)
- try to make bitbake less fragile
  - have a way to freeze/sign a recipe collection for a known-good
  distro?
- canonicalize workarounds to issues caused by autoconf badness
(inability to support cross-building)

Tim and Phil both said that contract money might not influence their contribution levels (they are maxed out now). Changing their focus with money might be detrimental (it might just take the fun out of it.) So, outside contractors seems like the better way to go for now.