I'll start with my question (so you can decide whether you care to read
the rest):
What is the BitBake equivalent of "Hello, World!?"
Specifically, what is the minimum project structure that
correctly describes a single layer and a single recipe?
--------------------------------------------------
I'm trying to understand Yocto and BitBake thoroughly. As a start, I tried
to construct a "minimal" BitBake project, with no Yocto content.
I began by running BitBake in an empty directory and fixing each error in
turn. Eventually, I was able run BitBake without errors -- even though it
didn't actually *do* anything (which was fine).
After that, I created a single layer, and that worked fine.
Most recently, I tried to create a single recipe within my one layer. I'm
having problems I don't know how to solve.
At the bottom of this message, I show the full structure of my tree and
the contents of all the files. Since the project is "minimal," there isn't
much to show.
>From within the "build" directory of my project, I ran BitBake like this:
$ ../BitBake/bin/bitbake
Nothing to do. Use 'bitbake world' to build everything,
or run 'bitbake --help' for usage information.
That's what I expected. Then, I tried to examine the layers:
$ ../BitBake/bin/bitbake-layers show-layers
layer path priority
=========================================================
LayerA /home/pturley/Workspace/woohoo/LayerA 0
That's also what I expected. Things went wrong when I tried to examine the
recipes:
$ ../BitBake/bin/bitbake-layers show-recipes
Parsing recipes..$
That's wrong. I expected something like this:
Parsing recipes..done.
=== Available recipes: ===
a:
LayerA 1
At first, "base.bbclass" was empty so, on a hunch, I added this:
do_hello() {
echo Hello
}
addtask hello
That changed the output to this:
$ ../BitBake/bin/bitbake-layers show-recipes
Parsing recipes..done.
=== Available recipes: ===
a:
? 1
This is still wrong, but better (though I can't explain why).
At this point I thought it best to look for experts. I don't need
hand-holding - but I *do* need substantive, accurate hints. If you have
any, I'd be grateful.
--------------------------------------------------
Here is the tree of files in my "minimal" project, along with the contents
of those file:
/home/pturley/Workspace/woohoo
|
+-- build
| |
| +-- classes
| | |
| | +-- base.bbclass
| |
| | +-------------------------------------------
| | | do_hello() {
| | | echo Hello
| | | }
| | |
| | | addtask hello
| | +-------------------------------------------
| |
| +-- conf
| |
| +-- bblayers.conf
| |
| | +-------------------------------------------
| | | BBLAYERS ?= " \
| | | /home/pturley/Workspace/woohoo/LayerA \
| | | "
| | +-------------------------------------------
| |
| +-- bitbake.conf
|
| +-------------------------------------------
| | CACHE = "${TOPDIR}/cache"
| +-------------------------------------------
|
+-- LayerA
| |
| +-- a.bb
| |
| | +-------------------------------------------
| | | PN = 'a'
| | | PV = '1'
| | +-------------------------------------------
| |
| +-- conf
| |
| +-- layer.conf
|
| +-------------------------------------------
| | BBPATH .= ":${LAYERDIR}"
| | BBFILES += "${LAYERDIR}/*.bb"
| +-------------------------------------------
|
+-- BitBake ...
The BitBake directory origin is:
http://git.openembedded.org/bitbake/
I have the 1.15.2 tag checked out, which is what
Yocto denzil uses.
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