[yocto] [Yocto] RFC: Image Creator and Config Creator, design thoughts

[Bruce Ashfield]

On 11-04-22 11:10 AM, Tom Zanussi wrote:
> On Thu, 2011-04-21 at 09:05 -0700, Darren Hart wrote:
>> I sat down with Josh earlier this week to discuss how I might use the
>> Image Creator in my development and to address any issues that might
>> pose as blockers to my finding such a tool useful. This led to various
>> feature discussions, scope setting, etc. I wanted to capture that here
>> and also ask for comments from other users and developers.
>>
>>
>> Image Recipe Generation
>> -----------------------
>> The image creator Josh is working on currently facilitates specifying
>> the policy (bitbake term "distro", such as poky, poky-bleeding, or
>> poky-lsb), image, and any additional packages you may want to include.
>> It then provides a simple wrapper to bitbake and it's output. This is
>> useful in and of itself as sorting out which variables to modify
>> (IMAGE_INSTALL, MACHINE(_ESSENTIAL?)_R?DEPENDS_append(_$MACHINE), etc)
>> and which tasks to rebuild (task_base, task_machine_base, poky-image-*,
>> etc.) can be a frustrating exercise (or at least it has been for me).
>>
>> In order for this feature to be the most useful, it needs to be able to
>> save the result of the user's selection. This involves saving off the
>> "distro" selection (typically in local.conf) as well as an image recipe
>> defining which packages to include in the resulting image. This could be
>> done by writing to local.conf and saving a new *image*.bb file in a
>> suitable location.
>>
>>
>> Writing Layers
>> --------------
>> The suitable location is most likely a layer, which suggests the Image
>> Builder should probably know how to construct a basic layer skeleton and
>> prompt the user to fill in the descriptive bits required for layer.conf.
>>
>> I could see this as having been useful for the recent Yocto Project 1.0
>> launch demo we worked on, which added rygel upnp video renderers to the
>> the 0.9 audio only demo. This implies the Image Builder should also be
>> able to work with an existing layer - perhaps only those that it created
>> - and save the changes back to that layer.
>>
>>
>> Configuration Fragments
>> -----------------------
>> In order to properly build the demo images (poky-image-rygel
>> specifically) some specific license related variables need to be set,
>> typically in local.conf:
>>
>> COMMERCIAL_LICENSE = ""
>> COMMERCIAL_AUDIO_PLUGINS ?= "gst-plugins-ugly-mad
>> gst-plugins-ugly-mpegaudioparse"
>> COMMERCIAL_VIDEO_PLUGINS ?= "gst-plugins-ugly-mpeg2dec
>> gst-plugins-ugly-mpegstream gst-plugins-bad-mpegvideoparse"
>>
>> Without the above, the upnp demo is mostly non-functional. Having to
>> manually add these sorts of settings significantly reduces the value of
>> the Image Builder in my mind. This led to the discussion of providing a
>> graphical mechanism to set the variables that have some impact on how
>> the generated image recipe is built.
>>
>> Something like a Linux kernel kconfig mechanism, which only shows the
>> user relevant options (albeit still WAY too many), might be really nice
>> here. Perhaps an interface that parsed the recipes included in the image
>> recipe and determined which variables would be relevant to the user and
>> present those in the UI with help derived from documentation.conf
>> doctags (or perhaps a new mechanism).
>>
>
> Input we got from the ELC talk suggested that people did think it would
> be intuitive and useful to expand the kernel menuconfig 'UI' down to all
> the other packages in the image.
>
> I've used UIs designed like that in other build systems and it was very
> useful, so I'd add my +1 to the ELC requests...

And I'd add another +1 to that.

Bruce

>
> Tom
>
>> As this would be a considerable effort, and would surely delay the
>> progress of the image builder itself, perhaps a Configuration Editor
>> would be a good companion tool which the Image Builder could launch to
>> do the relevant configurations
>>
>>
>> Conclusions
>> -----------
>> The goal of any user interface should be to abstract away to
>> implementation details that are not particularly relevant to task at
>> hand, or to the user's perception of the task at hand.  I feel these
>> tools as discussed above would help contain feature creep, while still
>> allowing for a more complete graphical interface to configuring and
>> building images.
>>
>>
>> Thoughts? Criticisms?
>>
>>
>
>
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