[yocto] how to set particular changes to a default kernel config

[lothar at denx.de]

Hi, thank you very much for your answer!

So, you mean something like this in the kernel .bb:
   require recipes-kernel/linux/linux-yocto.inc
This is definitely missing. I'm including linux.inc changing it to  
linux-yocto.inc breaks other patches that I'd like to apply (perhaps  
the path?). This means more work, and more doubts, too.

Now I'm asking myself, actually, should I change it from linux.inc to  
linux-yocto.inc generally?

At the moment, I'll apply the CONFIG_'s with "echo", which seems  
easier for the simple case.
BR,
L


Zitat von Bruce Ashfield <bruce.ashfield at windriver.com>:

> On 13-07-24 09:05 AM, lothar at denx.de wrote:
>> Dear Yocto Team,
>>
>> For an ARM based board (MACHINE = "myboard"), I use a default kernel
>> config from arch/arm/configs and want now to change some particular
>> CONFIG_ options.
>>
>> Trying to follow the documentation, I currently have the following files:
>> .
>> +- linux-acme
>> |   |
>> |   +- additional.cfg
>> |
>> +- linux-acme_3.8.bb
>>
>>
>>
>> ...in linux-acme_3.8.bb I have
>> (...)
>> S = "${WORKDIR}/git"
>> (...)
>> KERNEL_DEFCONFIG_myboard = "blabla_defconfig"
>> do_configure_prepend_myboard() {
>>      install -m 0644 ${S}/arch/${ARCH}/configs/${KERNEL_DEFCONFIG} \
>>            ${WORKDIR}/defconfig || die "no default config"
>> }
>> SRC_URI_myboard = "git://kernel.ubuntu.com/ubuntu/linux.git;protocol=git \
>>            file://additional.cfg"
>> (...)
>>
>>
>> ...and in additional.cfg I have
>> CONFIG_DEVTMPFS_MOUNT=y
>> CONFIG_MTD_CMDLINE_PARTS=y
>> CONFIG_MTD_BLOCK=y
>> CONFIG_MTD_M25P80=y
>>
>>
>> When I run something like...
>> $ bitbake -b /yocto/meta-myboard/recipes-kernel/linux/linux-acme_3.8.bb -f
>> ...it seems to find the .cfg file, since it stoped complaining (after I
>> fixed some paths) and now compiles/builds smoothely.
>>
>> Anyway, I can't see the changes in the .config in
>> $BDIR/tmp/work/myboard-linux-gnueabi/linux-acme/3.8+..../git/.config
>>
>> I imagine something like mixing both configs and running "make
>> oldconfig" in behind. Anyway before compilation, the changes should be
>> in the .config, right?
>>
>> Questions:
>> 1) How can I add single additional options to a default kernel config?
>
> Just like you have above, but does your recipe inherit linux-yocto ?
> You of course also need to have the dependencies of the options
> you are trying to add, otherwise, they won't make the final .config.
>
>> 2) What is the best way to check if the options were applied?
>
> There's an audit phase that runs after configuration has completed, but
> if you are using a different tree than the linux-yocto tree, it will
> do it's best to tell you what is missing, but needs to sift through
> a lot of data.
>
> A faster way for small changes is likely just what you are doing,
> checking the .config in the build dir.
>
>> 3) Do I need another approach, e.g. through a patch, using echo, or
>> using a .scc file (I tried, but with the same result)?
>
> Those will work as well, but the system will detect lonely .cfg files
> and apply them to the tree after the default configuration.
>
> Cheers,
>
> Bruce
>
>>
>> Best Regards,
>> Lothar Rubusch
>>
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>
>