[linux-yocto] Locating kernel metadata

[Peter A. Bigot]

Thanks for the additional information. My entire expectation of how 
linux-yocto metadata worked turns out to be wrong, but you've managed to 
clear it up for me.

What I really wanted from linux-yocto was a way to isolate documented 
kernel configuration fragments to share configuration data among a set 
of related BSPs, and keep particular features (such as OMAP ISP) out 
unless a particular build desired that feature.  The linux-mainline 
approach of a monolithic defconfig with no comments explaining why 
particular Kconfig options are set is itself unmaintainable, especially 
when updating to new kernels where names change.

That linux-yocto is designed to support building kernels for multiple 
BSPs simultaneously from a shared metadata hierarchy is an architectural 
driver that was not clearly communicated. Perhaps because that need is 
completely irrelevant to my goals so I didn't notice it mentioned 
before.  It also explains why I failed to communicate my discomfort with 
the way recipe-space metadata is handled differently from in-tree metadata.

For your case in-tree metadata (by which I mean scc and cfg files in 
particular) needs to be untouched because it's shared.

For me it has pieces that are wrong and that should be overridden in a 
distinct step so I can review in-place the metadata that the kernel 
tools are actually going to use to construct the config file.  I thought 
SRC_URI provided a way for me to override those files prior to their 
being interpreted, rather like providing a default config file to be 
copied into the source tree.  In fact linux-yocto is much more active 
than I expected when it unconditionally processes the scc files in 
SRC_URI during fetch, rather than only if they're referenced from the 
root BSP description.

At this point I need to go try to see how to do what I want to do within 
the current framework.  Prior to this my attempts failed because I 
couldn't figure out what the tools were doing with my metadata; now I 
have more clues and may be able to make progress.

On 09/01/2013 12:30 AM, Bruce Ashfield wrote:
> On 13-08-31 12:07 PM, Peter A. Bigot wrote:
>> Let's start by defining terms that I think don't exist or aren't used
>> consistently.  In what follows:
>
> Some of what you may be missing is in the "kernel architecture" manuals,
> which I wrote ages ago .. and which we subsequently moved to a harder
> to find area of the Yocto site .. since they contained too much detailed
> information that wasn't generally useful.

I think a pointer to this kernel architecture documentation belongs in 
the YPLKDM "Other Resources" section.  I've added bug 5093 to address 
this for 1.5.  In the meantime, perhaps you could provide a link here?

Thanks again.

Peter