[yocto] bsp experiences

[Frans Meulenbroeks]

2012/5/1 Tom Zanussi <tom.zanussi at intel.com>:
> Hi Frans,
>
> Thanks for your input, comments below...
>
> On Tue, 2012-05-01 at 16:21 +0200, Frans Meulenbroeks wrote:
>> Dear all,
>>
>> In this email I'd like to share my experiences wrt creating a new bsp.
>> I hope this is useful for someone (e.g. for updating the doc). Feel
>> free to point out the n00bish errors I made, or where I could have
>> improved.
>>
>> Aim was to bring my current board (powerpc mpc8313e based) onto yocto 1.2
>> This board is already working under oe classic.
>>
>> I started fetching poky-denzil-7.0.
>> Tested by building core-image-minimal. No problems here.
>>
>> Then I wanted to add my own bsp. Decided to use the bsp-guide as a starter.
>>
>> Tried to use yocto-bsp with the standard 7.0 setup (where there is a
>> poky-denzil-7.0-build dir adjacent to the soruce dir).
>> yocto-bsp when invoked complained with:
>> IOError: [Errno 2] No such file or directory:
>> '/home/frans/poky-denzil-7.0/scripts/../build/conf/bblayers.conf'
>>
>
> This should be fixed by the fix for this bug:
>
> https://bugzilla.yoctoproject.org/show_bug.cgi?id=2219
>
> which didn't make it into the release, and hasn't been pulled into
> master yet either...
>
> But actually that should only apply to yocto-kernel, not yocto-bsp.
>
> Can you provide more info on your exact setup and commands you used?

I just downloaded denzel according to the quickstart guide.
My build dir was outside the source tree.

I did
    $ wget http://downloads.yoctoproject.org/releases/yocto/yocto-1.2/poky-denzil-7.0.tar.bz2
     $ tar xjf poky-denzil-7.0.tar.bz2
     $ source poky-denzil-7.0/oe-init-build-env poky-denzil-7.0-build
Tweaked local.conf a little (parallel make and bbthreads and rm_work).
Then build core-image-minimal for for the standard machine (x68 emu or so)

after that in the build dir I did (if I recall correctly)
yocto-bsp create mpc8313 powerpc

That gave the error.
I think the exact message is still on the console of my build system
at work. Will check, if so I can email it tomorrow.

>
>> I resolved this for now by making /home/frans/poky-denzil-7.0/build/ a
>> symlink to /home/frans/poky-denzil-7.0-build
>> Not sure if that is the desired solution but anyway this allowed me to
>> move forward
>>
>> Reinvoked yocto-bsp create, this indeed gave progress.
>> Now had to decide on the machine branch to start this on. As mpc8315
>> is fairly close decide to start with that one.
>> tuning support was a bit tough. The 8313 machine conf file in
>> oe-classic said ppce300c3, so used ppce300c2 as a starter
>> next modified the file that contains the device tree to the default 8313 dts.
>>
>> That generated the layer.
>> Still had to add the layer to bblayers.conf (I was somewhat surprised
>> by this as the script before complained about not being able to find
>> that file so I somehow expected it to be added automatically)
>>
>
> The tools are conservative about changing anything outside of what they
> generated - not sure it makes sense to have them changing
> bblayers.conf...

That's ok.
After sending my mail I noticed that the doc says that one needs to
update bblayers.conf

It might be an idea to let the script spit out a message that the user
still needs to do this though.

>
>> Also went to conf/machine in my bsp and changed it to use
>> tune-ppce300c3 instead of c2, and created this include file by copying
>> the c2 file to c3 and renaming all references to c2 by c3 (as these
>> were the only changes when comparing the oe classic c2 and c3 tune inc
>> files.
>>
>> While building core-image-minimal, building the kernel failed because
>> recipes-kernel/linux/linux-yocto_3.2.bbappend had some references to
>> mpc8315*. Replaced these with mpc8313*. (not fully sure if that is
>> fully sound though; anyway I need to hack the kernel part anyway).
>> And now, while typing this, things are happily humming along, giving
>> me time to type this message.
>>
>
> The ppc template support is pretty much untested - I focused only on
> platforms I had hardware support for and didn't do much with the others,
> as mentioned in the submission.
>
> So I'll be happy to change the templates to make them match reality and
> be more useful out-of the box for those platforms I don't know much
> about.
>
> The other thing to note however is that the tool is meant to give a
> starting point which will likely need to be tweaked in order to actually
> work on the hardware.  It should at least compile, though...
>

Understood. I'm not too sure how well the template works.
I'm still in the process to migrate (knowledgewise) from oe-classic to yocto.
If I find out how to improve the template (or something else), I'll
let you know (or submit a patch)

Keep up the good work!
Frans