On 2016-05-10 9:57 AM, Chris Trobridge wrote:
Thanks Joel,

I can build the module but I am trying to find out the best way to do
this with yocto/bitbake.

The build process for the second module I have requires the location of
the first and then does copy the Module.symvers and accesses the header
files and ".version" file.

The question was more about how it should find these.

What I have just tried out, is to copy the above files  (Module.symvers,
.version and include/* to ${STAGING_KERNEL_BUILDDIR}/out-of-tree/${PN},
which is hence easily accessible by the second recipe.

This works but may not be the preferred way?  I suspect the preferred
way is to build in the kernel.

Having two external modules that depend on symbols is indeed a case
that isn't explicitly in the current workflow. As was pointed out, we
did solve the case where an external module required symbols from
a module from the kernel (that extra copy to the shared workdir of the
updated Module.symvers).

If you have two out of tree modules that have a dependency, then you
do need to arrange to have the symbol information available to the
second module. What you did is pretty much the right way, you could
also update the kernel shared workdir, but you'd have to be careful
to not race with the main build, and also to not clobber symbols from
the kernel and in-tree modules.

Bruce


Cheers,
Chris

------------------------------------------------------------------------
From: joel.espo...@honeywell.com
To: christrobri...@hotmail.com; yocto@yoctoproject.org
Subject: RE: [yocto] Formulating Recipe for out-of-tree kernel module
Date: Tue, 10 May 2016 13:29:30 +0000

Ok! I better understand your need now.

The fix solves the case where an out of tree module is dependent of a
kernel module which is not built as a built-in module.



Just in case, did you have a look on these links?

http://stackoverflow.com/a/33718934/1729117

https://www.kernel.org/doc/Documentation/kbuild/modules.txt (Chapter 6.2
and 6.3)



*Joël Esponde*

*Honeywell *| Sensing and Productivity Solutions



*De :*Chris Trobridge [mailto:christrobri...@hotmail.com]
*Envoyé :* mardi 10 mai 2016 13:28
*À :* Esponde, Joel; yocto@yoctoproject.org
*Objet :* RE: [yocto] Formulating Recipe for out-of-tree kernel module



Thanks Joel,



I am on Krogoth.



My reading of that patch is that it allows out-of-tree modules to depend
on symbols from the kernel but I don't see how it would help with
depending on another out-of-tree module?  Those symbols are not added to
the kernel Module.symvers.



I've been following some other usage I read that 'out-of-tree' means
compiling outside/after the kernel build, which may not be 100% accurate?



Anyway, it suggests to me that copying the first module's Module.symvers
to the shared kernel staging area and then referencing that from the
second module is probably better than my current solution, provided I
don't break any conventions on using the staging area.



Cheers,

Chris

------------------------------------------------------------------------

From: joel.espo...@honeywell.com <mailto:joel.espo...@honeywell.com>
To: christrobri...@hotmail.com <mailto:christrobri...@hotmail.com>;
yocto@yoctoproject.org <mailto:yocto@yoctoproject.org>
Subject: RE: [yocto] Formulating Recipe for out-of-tree kernel module
Date: Tue, 10 May 2016 10:06:37 +0000

Hi,



There is a bitbake issue that prevents building an out-of-tree module
that is dependent of another out-of-tree module.

This issue has been fixed recently:

http://git.yoctoproject.org/cgit/cgit.cgi/poky/commit/?h=master-next&id=a9cc27e6916e5affe8b0cc431c3e89abd7681643



This fix has been released on yocto 2.1 (krogoth).

So if you are using an older Yocto project, you will have to fix two
recipes manually.



I hope this will help!



*Joël Esponde*

*Honeywell *| Sensing and Productivity Solutions



*De :*yocto-boun...@yoctoproject.org
<mailto:yocto-boun...@yoctoproject.org>[mailto:yocto-boun...@yoctoproject.org]
*De la part de* Chris Trobridge
*Envoyé :* mardi 10 mai 2016 08:59
*À :* yocto@yoctoproject.org <mailto:yocto@yoctoproject.org>
*Objet :* Re: [yocto] Formulating Recipe for out-of-tree kernel module



At the risk of answering my own question...



Splitting a driver package into a module recipe and a separate recipe
for user-mode utilities works in that each recipe uses the appropriate
build process and puts files in the appropriate subdirectory of /work/.



I still don't see a way to build one out-of-tree module against another.
 I am interested in opinion on this.  Should I try to get these drivers
built in tree?  They seem to be the only two out-of-tree drivers in the
build at present.  There is also some facility to add extra modules to
the dahdi linux build, although achieving this with bitbake could be
challenging too.

Cheers,

Chris

------------------------------------------------------------------------

From: christrobri...@hotmail.com <mailto:christrobri...@hotmail.com>
To: yocto@yoctoproject.org <mailto:yocto@yoctoproject.org>
Date: Mon, 9 May 2016 12:15:26 +0100
Subject: [yocto] Formulating Recipe for out-of-tree kernel module

I am looking to produce a recipe for the amfeltec usb-fxs adaptor
(http://amfeltec.com/products/piranha-usb-fxs-adapter/), with the
intention of contributing this to the meta-telephony layer.



However, I have found a few obstacles to getting a clean recipe:

  * The makefile produces both a kernel module and a user utility, with
    the latter being hard-coded to build with g++.  I can produce a
    recipe to produce one or other of the components but not both.
     Given the structure of the build directories, should this be be
    achievable, or should I be spitting up the recipe in two?
  * Dahdi header files and Modules.symvers are required.  A header file
    is used to deduce the version of Dahdi, Modules.symvers is required
    for the module build process.  Hence, requires the location of the
    Dahdi source/build directory.  This can be set relative to the
    amfeltec work directory but this feels wrong.



In more general terms my questions are:

  * Should I split a recipe into kernel and non-kernel components?
  * How should one out-of-tree recipe access the headers/Module.symvers
    from another (should that recipe be installing them in
    ${STAGING_KERNEL_DIR} (or somewhere else)?)



Cheers,

Chris




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