[meta-ti] [PATCH] adjust BBPATH to be a good citizen of layer world

[Khem Raj]

On Nov 7, 2013, at 10:20 AM, Denys Dmytriyenko <denys at ti.com> wrote:

> On Thu, Nov 07, 2013 at 09:57:09AM -0800, Khem Raj wrote:
>> 
>> On Nov 7, 2013, at 9:47 AM, Denys Dmytriyenko <denys at ti.com> wrote:
>> 
>>> On Thu, Nov 07, 2013 at 09:42:50AM -0800, Khem Raj wrote:
>>>> 
>>>> On Nov 7, 2013, at 9:37 AM, Denys Dmytriyenko <denys at ti.com> wrote:
>>>> 
>>>>> On Thu, Nov 07, 2013 at 09:15:40AM -0800, Khem Raj wrote:
>>>>>> 
>>>>>> On Nov 7, 2013, at 8:59 AM, Denys Dmytriyenko <denys at ti.com> wrote:
>>>>>> 
>>>>>>> On Wed, Nov 06, 2013 at 08:55:55PM -0800, Khem Raj wrote:
>>>>>>>> On Wed, Nov 6, 2013 at 8:29 PM, Maupin, Chase <chase.maupin at ti.com> wrote:
>>>>>>>>> This seems like a reversal of http://arago-project.org/git/meta-ti.git?a=commit;h=dabd83e96fe99d0c3d1a88be4d1637831526d217
>>>>>>>>> 
>>>>>>>>> Looks like there may be a need to cover the different use cases and 
>>>>>>>>> understand what each person is trying to do :)
>>>>>>>>> 
>>>>>>>> 
>>>>>>>> ah I see what caused this all pain. So now meta-ti is odd ball out.
>>>>>>>> this patch should have never gone in.
>>>>>>> 
>>>>>>> Khem,
>>>>>>> 
>>>>>>> If you remember, we discussed this with Richard and he suggested this as a 
>>>>>>> solution to the ordering problem. Otherwise people tend to append any extra 
>>>>>>> layers _after_ oe-core, which should be the other way around in order to 
>>>>>>> override anything in there…
>>>>>> 
>>>>>> I think the problem is when you have many other layers then the whole 
>>>>>> paradigm changes to it and you end up with same issue upside down. I think 
>>>>>> how you order bblayer.conf can control the override of oe-core, I wish if 
>>>>>> distro’s could control the layer.conf for each bsp layer then it wouldnt 
>>>>>> matter as much
>>>>> 
>>>>> I agree this is a bigger issue. I looked at some layers and found few that 
>>>>> prepend themselves, while most of others just append.
>>>>> 
>>>>> The order inside bblayers.conf is much more important than people let to 
>>>>> believe. For example, if multiple layers define the machine config, the first 
>>>>> one listed in bblayers.conf wins - this is a real problem for beagleboard.conf 
>>>>> that is currently being defined in meta-ti as well as meta-yocto-bsp (as a 
>>>>> reference platform) and meta-beagleboard too. Very soon the same problem will 
>>>>> happen to beaglebone.conf, when meta-yocto-bsp picks it up as a reference...
>>>>> 
>>>>> Anyway, the biggest issue I'm trying to work around with this change is the 
>>>>> "shadowing" of the new-style DTBs that I ported from Dora to Dylan. If meta-ti 
>>>>> is not in front of oe-core, the old-style DTBs come into play and DTBs are not 
>>>>> built at all. So, this is not really an issue for Dora or master, and those 
>>>>> don't need to be prepended after all…
>>>> 
>>>> 
>>>> Now its even more intriguing since you changed meta-ti/master and I would 
>>>> have expected this change to show up in meta-ti/dylan or are you claiming 
>>>> all sort of oe-core branches to work with meta-ti/master thats a perilous 
>>>> path.
>>> 
>>> It's in meta-ti/dylan AND meta-ti/master,
>> 
>> yes. So can we change the master please ?
> 
> I'll think about it ;)
> 
> 
>> oe-core is also appending itself in BBPATH in oe-core/master
> 
> Yes, I know.
> 
> 
>> and so are meta-yocto-bsp and meta-beagleboard 
> 
> Also quite aware of that.
> 
> But since you mention meta-yocto-bsp, which is part of Poky, do you know that 
> meta-yocto prepends itself in front? And I believe there were one or two more 
> obscure layers doing that as well…

we can coerce them to change as well. if I have time I will go through
this on layers index. Its good in general to have this since its beneficial
and does larger good.

> 
> BTW, I like the comment you made in meta-oe long time ago:
> 
> # It really depends on order of the layers appearing in BBLAYERS
> # variable in toplevel bblayers.conf file, where bitbake will search
> # for .inc files and others where bitbake uses BBPATH since it will
> # search the directories from first to last as specified in BBPATH
> # Therefore if you want a given layer to be considered high priority
> # for the .inc and .conf etc. then consider it adding at the beginning
> # of BBPATH. For bblayers bitbake will use BBFILES_PRIORITY to resolve
> # the recipe contention so the order of directories in BBFILES does 
> # not matter.
> 
> But the problem is that people don't read comments and don't bother with 
> BBLAYERS order, hence I had to do what you suggested above with BBPATH order 
> instead!


amen

> 
> 
>> so with mere ordering of these layers in your distro’s bblayer.conf you 
>> should be able to get desired behaviour.
> 
> Well, it's not really a problem for Arago or Angstrom, as both provide setup 
> tools to generate the correct bblayers.conf with the proper order of BBLAYERS. 
> But the problem is really with Poky, as it expects people to manually add 
> extra layers to bblayers.conf and people just tend to append everything AFTER 
> oe-core and meta-yocto and meta-yocto-bsp. So, it's really Poky that is broken 
> or rather unclear…

yes and I think as long as all layers follow append model it will bring some santiy
to poky model as well.