[poky] Impressions of using Poky to create a BSP

[Bruce Ashfield]

On Fri, May 27, 2011 at 1:42 PM, Holger Freyther <holger at freyther.de> wrote:
> Hi all,
>
> I hope these impressions are useful. In the last two days I added a BSP for a
> TI Davinci based system and I am afraid it was a bit harder than I think it
> should be. This is a summary of the underlying issues (without them being
> debugged or completely understood).
>
> meta-skeleton and BBFILES:
>   - Maybe it would be nice if the file glob would list *.bbappend as I think
>     many people want to use it.
>
> BBLAYERs and dependencies:
>    - I had changed BBFILES to list *.bbappend but the change didn't take
>      effect. I had to touch conf/local.conf to force a re-parse. So somehow
>      the layers config didn't end up in dependencies.
>
> fetch vs. fetch2:
>    - I wanted to fetch my kernel from my internal git/ssh repository. I was
>      not sure where to put the username (git://foo@bar or git://bar;user=foo)
>      so I was experimenting a bit. This triggered me being banned from my
>      server (fail2ban) so the git process on the buildhost got stuck and I
>      backgrounded bitbake with CTRL+Z.
>
>    - Then I tried bitbake -cfetch virtual/kernel again and it didn't do anything,
>      it took me a while to think that it might wait on a lock. I think it would be
>      great if this could be printed somewhere (if my understanding of this is
>      correct).
>
>    - Also it was not obvious to find out which of the two fetchers are used..
>
>
> Adding a kernel:
>     - So by default the linuxdummy is used, but I wanted to build my kernel,
>       I started off by copying the yocto kernel recipes. This creates a very funny
>       bug. My kernel didn't have the meta branch, the task to test the branches
>       executes git log for the branch and this is failing.
>       The symptoms are not obvious at all. An empty log file is left behind.

Was this out of master ? There's been some commits and sanity checks
added just recently that emit clear messages if you don't have things like
the meta branch, or the right configuration. Auto creation of meta data is
also in the tree now.

This is also a failing of the docs if this wasn't clear, we can look into that
as well.

>
>     - I was using the yocto kernel recipes incorrectly and ended up with a logfile
>       that pointed to itself for details but nothing else.
>
>     - In the end I used a minimal kernel recipe, it would be nice to either have
>       an easy way to 'produce' a yocto like kernel of a simple kernel recipe in
>       the skeletons.

There's a 1.1 feature for this, and it will actually be sent out
shortly. There's
the ability to auto create meta data, using any upstream source, and the
ability to build from arbitrary upstream repos.

Both of these are supposed to be transitional aids though, since if you are
basing something on the linux-yocto kernel(s), it's best to actually use the
uptream kernel (branches and all) and create BSP branches on it.

>
> Python Exceptions:
>     - Building something that is not provided gives a python exception
>     - Adding a task that does not exist gives a python exception
>     - I think it would be nice to have meaningful error messages. Specially
>       the laters runs into something like:
>      if not Data:
>           print "BLA BLA"
>      use(data)
>
> Machine Extra Depends:
>     - I was using the core-minimal-image but wanted to have some of my
>       kernel modules installed. After finding the name that task-core-boot
>       is using I tried to do bitbake -cclean task-core-boot; bitbake the-image
>       but this didn't end up with a task-core-boot to carry my depends.
>       I had to resort to using bitbake -b task-core-boot.bb to build  it, I am not
>       sure why it failed when running from within the normal bitbake. IIRC it
>       continued to be like this even after I removed tmp/cache.
>
> I hope this point of view is helpful.

It' definitely helps me, I think a lot has already been addressed, and this
should be a seamless process from the kernel build point of view.

cheers,

Bruce

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