Re: one way hash analogy of yocto

Quentin Schulz

Hi Robm

On Fri, Jul 31, 2020 at 08:45:17AM -0400, Rob Prowel wrote:
What I really need is information about introspection or the ability to
query an existing yocto distro to return data about features included and
more to the point, to understand EXACTLY where recipes or classes are
overridden or appended. You can only do so much with recursive grep and
find scripts. Based on what I've seen so far, it seems that capability is
lacking in yocto.

In essence I have what is like a one way hash ABCDEFG-->X and I have X but
cannot fully figure out the whole input that generated it.

An example would be an overridden task method like


I need a quick way to determine the highest priority level that task was
overridden or appended in for a given recipe.

a command like "bitbake -describe -c do_something my-recipe"

and it should also be possible to query this kind of information for
variables and not just methods or tasks.

Do these tools exist or am I looking at parsing megabytes of verbose build
data and tracing output to find what I'm looking for?
For location of bbappends and recipes, etc.:
bitbake-layers show-appends
bitbake-layers show-recipes

For variables:
bitbake <recipe> -e | more
and find the line starting with the variable you're looking for. From
there, look the lines just before and you'll have the history of how the
variables was constructed.

bitbake <recipe> -e | awk '/^# \$FOOBAR \[/,/^FOOBAR/'
might do it for you. Not tested by me so can't attest. (source:

I do not know if there is such a mechanism for tasks, but the
bitbake-layers should help you get started in your quest of overridden

Also, I'm not sure it matters much where the tasks are overridden? Just
override them again with your own bbappend (especially if it's a layer
you don't own (read upstream or provided by vendor)).


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