[yocto] bsp experiences

Tue May 1 13:36:45 PDT 2012

On Tue, 2012-05-01 at 22:23 +0200, Frans Meulenbroeks wrote:
> 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.
> 

No need, I just tried it myself here using the instructions from your
e-mail of a few minutes ago and saw the error after a couple steps
through.

The following patch fixed it:

http://git.yoctoproject.org/cgit/cgit.cgi/poky-contrib/log/?h=tzanussi/yocto-bsp-fixes-2219-2330

I can't fix it in the release of course, but I'll at least submit a
patch to the release notes and the quick start...

> >
> >> 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)
> 

Either way would be great.  Basically the templates are just BSP files
with markup inside that provide sets of options.  Even if you just had a
set of BSP files for powerpc that you think would be good for providing
a generic starting point, I (or you) could translate those into a BSP
template and we could add options for various things like tuning files
on top of that.

Thanks,

Tom

> Keep up the good work!
> Frans