[yocto] Fwd: How do I control what kernel modules are being loaded?

[Hans Beckérus]

On Sat, Mar 9, 2013 at 12:45 AM, Bruce Ashfield <
bruce.ashfield at windriver.com> wrote:

> On 13-03-08 2:00 PM, Hans Beckerus wrote:
>
>> On 2013-03-08 7:12, Eric Bénard wrote:
>>
>>> Hi Hans,
>>>
>>> Le Fri, 8 Mar 2013 13:08:21 +0100,
>>> Hans Beckérus <hans.beckerus at gmail.com> a écrit :
>>>
>>>  Hi. I have built some custom kernel modules (.ko) using a .bb that
>>>> inherits from the module.bbclass. There is one main kernel module and
>>>> the rest are dependent on the first. Building and installing the
>>>> modules to the rootfs works fine. Next question is how do I control
>>>> what actual modules are loaded at boot, or actually how do I control
>>>> this through Yocto? To my surprise one of the kernel module loaded
>>>> automatically!? How could this happen? I did not have an entry for it
>>>> in /etc/modules. And what do I need to do to actually add entries to
>>>> /etc/modules? Or is there some other mechanism that I should use. I
>>>> tried going through the module.bbclass but must admit I lost it
>>>> somewhere in the middle ;) Any guidance would be appreciated.
>>>>
>>>>  when the module is built by the kernel recipe you can use :
>>> module_autoload and you can see somme usage examples here :
>>> http://cgit.openembedded.org/**meta-handheld/tree/conf/**
>>> machine/palmtx.conf<http://cgit.openembedded.org/meta-handheld/tree/conf/machine/palmtx.conf>
>>> http://cgit.openembedded.org/**meta-handheld/tree/conf/**
>>> machine/include/palm.inc<http://cgit.openembedded.org/meta-handheld/tree/conf/machine/include/palm.inc>
>>>
>>>
>>> maybe you could get inspiration from kernel.bbclass to do the same
>>> thing in your recipe.
>>>
>>> Eric
>>>
>> Thanks guys for your quick feedback. I can see that using
>> module_autoload_${PN} seems like a good approach, if a package maps 1:1
>> to a module.
>> In my case that is not so. The package/recipe builds six (or even more)
>> .ko files using one makefile.
>> I guess one option could be to split each module build in its own
>> recipe, but that is not supported by the makefile and thus would require
>> patching from my side in the source tree. I think the only option I have
>> left is to try to use /etc/modules and add the modules there in a
>> do_install_append().
>> But the problem then is, what happens if some other package also add a
>> /etc/modules.conf to the image folder? Will it be merged or only copied?
>> In the latter case last package wins which would not work out very well :(
>>
>> Out of curiosity, what will module_autoload do? Will it add the .ko to
>> /etc/modules or does it implement some other mechanism to make a module
>> load automatically at boot?
>>
>
> It depends on what release you are using. In yocto 1.3 and before the
> autoload variables translated to mod-util loading, using just what you'd
> think. In yocto 1.4 and kmod in the picture:
>
>         # If autoloading is requested, output /etc/modules-load.d/<name>.*
> *conf and append
>         # appropriate modprobe commands to the postinst
>         autoload = d.getVar('module_autoload_%s' % basename, True)
>         if autoload:
>             name = '%s/etc/modules-load.d/%s.**conf' % (dvar, basename)
>             f = open(name, 'w')
>             for m in autoload.split():
>                 f.write('%s\n' % m)
>             f.close()
>             postinst = d.getVar('pkg_postinst_%s' % pkg, True)
>             if not postinst:
>                 bb.fatal("pkg_postinst_%s not defined" % pkg)
>             postinst += d.getVar('autoload_postinst_**fragment', True) %
> autoload
>             d.setVar('pkg_postinst_%s' % pkg, postinst)
>
>         # Write out any modconf fragment
>         modconf = d.getVar('module_conf_%s' % basename, True)
>         if modconf:
>             name = '%s/etc/modprobe.d/%s.conf' % (dvar, basename)
>             f = open(name, 'w')
>             f.write("%s\n" % modconf)
>             f.close()
>
> Cheers,
>
> Bruce
>
> I do not have much luck getting this to work I am afraid. No matter what I
try with module_autoload it does not seem to have any effect on my system
(no file(s) created in /etc). I have tried adding module_autoload to both
my machine config and/or distro. I am running danny 8.0 which is version
1.3 of the poky distro I guess. I can see how module_autoload_%s is parsed
in kernel.bb but how is that recipe called as part om my module package? I
can not see that anything is inheriting from it so when is the
module_autoload supposed to be parsed and place files in in the package
/etc? Do I need to rebuild something other than my module package? My guess
Is that I should see something in the package image folder, or? All I see
is the lib folder holding the kernel module hierarchy and the .ko files of
course. I would really like getting this to work. Otherwise the only ugly
workaround I can see is to write my own simplistic init script that calls
modprobe on the modules I need after boot.

Hans
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