[yocto] Yocto and Google protobuffer

[Jussi Kukkonen]

On 1 September 2016 at 12:34, Pietro <pulsarpietro at posteo.net> wrote:

> Maciej Borzęcki
> <maciej.borzecki at rndity.com> writes:
>
> > On Thu, Sep 1, 2016 at 10:40 AM, Pietro <pulsarpietro at posteo.net> wrote:
> >> Maciej Borzęcki
> >> <maciej.borzecki at rndity.com> writes:
> >>
> >>> On Wed, Aug 31, 2016 at 6:44 PM, Pietro <pulsarpietro at posteo.net>
> wrote:
> >>>> Hi all,
> >>>>
> >>>> I am new to the Yocto building system and I could be talking
> nonsense. I
> >>>> used to work with buildroot time ago and I remember there is an area
> >>>> where compiled software/packages/tools previously built are "staged"
> and
> >>>> used when building other packages.
> >>>>
> >>>> Is there something like that available with Yocto ? Specifically I
> would
> >>>> like to add a package which uses the Google Protocol Buffer, I do not
> have
> >>>> administrator rights on the machine and I can't install the packages I
> >>>> need system wise.
> >>>>
> >>>> Is it possible to add recipes and use them at building time without
> >>>> including them in the image being generated ?
> >>>>
> >>>> A good example for that would be the protoc, the protocol buffer
> description
> >>>> file compiler.
> >>>>
> >>>
> >>> There is a recipe for protobuf in meta-oe (2.6.1). All you need to do,
> >>> is include meta-oe in your layers (bblayers.conf) and have
> >>> protobuf-native listed in DEPENDS inside your package recipe.
> >>>
> >>> The protoc compiler will be available in the PATH when package is
> >>> being built, so autotools checks like AC_CHECK_PROG/AC_PATH_PROG
> >>> should be able to find it.
> >>>
> >>> Cheers,
> >>> --
> >>> Maciej Borzecki
> >>> RnDity
> >> Thanks a lot.
> >>
> >> I have added the DEPENDS line and it indeed downloads and build the some
> >> protobuf related stuff, where did you get the dependency name from ?
> >> I can't see the protobuf-native as a recipe in the meta-oe website :
> >>
> >> https://layers.openembedded.org/layerindex/branch/master/layer/meta-oe/
> >
> > It's just a mechanism that allows for building the native (i.e. for
> > the host) packages, and these are autmatically named ${PN}-native.
> > There should a BBCLASSEXTEND = "..native.." stanza inside the protobuf
> > recipe that enables this feature.
> >
> >>
> >> I have just realised that GRPC (http://www.grpc.io/) is needed for my
> >> project, it is a library which uses the protobuffers, is there a
> >> recipe/package which provides them around or do I need to create my own
> >> recipe ?
> >
> > You can try searching for a recipe at http://layers.openembedded.org
> > If there's none, try to write your own. This might be a good changes
> > to get yourself acquainted with `devtool` tool that will help you in
> > the process.
> >
> >>
> >> I would like to check the root filesystem being generated as part of the
> >> build process, where is it ?
> >>
> >
> > ${TMPDIR}/<machine>_<distro?>/<imagename>/../rootfs
> >
> > for instance, for my current build:
> >
> > tmp/work/vexpress_qemu-poky-linux-gnueabi/core-image-
> minimal/1.0-r0/rootfs
> >
> > --
> > Maciej Borzecki
> > RnDity
>
> Thanks, much appreciated.
>
> Do you know where the software which is not included in the image - such
> us protoc - is it stored ?
>

The sysroots are in ${TMPDIR}/sysroots/: The native sysroot (probably
x86_64-linux) will be one of those.

The corresponding protobuf work directory will be in
${TMPDIR}/work/<target_system>/protobuf

See the Yocto dev manual and reference manual for more details about these.
http://www.yoctoproject.org/docs/current/dev-manual/dev-manual.html
http://www.yoctoproject.org/docs/current/ref-manual/ref-manual.html

HTH,
  Jussi
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