[yocto] Magic kernel config option.
Brian Smucker
bds at bsmucker.eu.org
Wed Jan 2 14:43:32 PST 2013
I take everything back. The entry in the defconfig did the trick. My
problem was that the recipe was grabbing its defconfig from the wrong
directory, costing me much confusion.
So sorry for the false alarm. Thanks again for your help. When you
said the defconfig was a straight copy, the light finally dawned that
there was something else going on.
The silver lining to all this thrashing around for me was the fact that
I do understand the kernel bitbake process much better.
Brian
On 1/2/2013 2:15 PM, Bruce Ashfield wrote:
>
>
>
> On Wed, Jan 2, 2013 at 4:47 PM, Brian Smucker <bds at bsmucker.eu.org
> <mailto:bds at bsmucker.eu.org>> wrote:
>
> On 1/2/2013 1:12 PM, Bruce Ashfield wrote:
>
> On 13-01-02 04:11 PM, Brian Smucker wrote:
>
> On 1/2/2013 10:06 AM, Bruce Ashfield wrote:
> > On 12-12-24 02:59 PM, Brian Smucker wrote:
> >> Hi,
> >>
> >
> > Catching up on email from the holidays. Did you ever
> get an answer
> > to this ?
> Not yet, resumed my quest today.
>
> >> I'm a yocto mostly-newbie, trying to find my way. I
> have a custom
> layer
> >> that I am using to build a kernel. The layer right now
> consists of a
> few
> >> kernel patches and a defconfig and is based on the
> standard kernel
> >> otherwise.
> >>
> >> When I do a diff on my defconfig and the bitbake
> generated .config,
> they
> >> are quite similar, but the CONFIG_UNION_FS=y line
> magically shows up.
> >> I'm wondering where it comes from and how to disable it.
> >
> > CONFIG_UNION_FS is being enabled by the standard kernel
> (and all
> > kernels that inherit it). Since you are based on that
> kernel, you
> > get the option enabled.
> >
> >>
> >> I can do a bitbake -c menuconfig virtual/kernel and
> eliminate that
> >> option giving me the kernel I want, but those changes
> are gone after a
> >> bitbake -c cleansstate ...
> >
> > Have you tried putting
> >
> > # CONFIG_UNION_FS is not set
> >
> > in your defconfig ? That should disable it.
> >
> I did try that, but that did not disable it.
>
>
> Hmmm. It worked here. I'll run another test shortly (I'm
> working on
> 3.8-rc1 at the moment).
>
>
> So after much pain and thrashing about to figure things
> out, now I see
> that in the standard-nocfg.scc file, the unionfs feature
> is set. This
> file is found in the following path: tmp/work/..
> ../linux/meta/cfg/kernel-cache/ktypes/standard/ directory.
>
> My current burning question is: Where is does this file
> come from? It
> does not seem to be part of the kernel git repository. I
> can changes
> this file and affect the kernel build, but again, those
> changes are
> transitory and do not persist after cleaning.
>
>
> It's from the meta branch of the kernel git repository. Those
> are all the fragments that are used to construct and configure
> the kernel. Part of the build process makes them available to the
> configuration phase.
>
> As something else to try, call your file <foo>.cfg and add it
> to the
> SRC_URI the same way you added the defconfig. defconfig's get
> special
> processing, calling it <foo>.cfg will simply get your changes
> added
> to the end of the build and they teka precedence.
>
>
> Tried your above suggestion, didn't seem to work.
>
> So with a bit of further testing it looks like by the time the
> defconfig and the <foo>.cfg are copied into the linux directory,
> the commented out config option: # CONFIG_UNION_FS is not set
> line is totally gone.
>
>
> Interesting .. and not really possible if you are talking about the
> version in $WORKDIR (i.e
> the directory above the linux/ source directory). Those are straight
> copies from your
> layer, with zero processing. Same with the copy within the
> linux/meta/cfg/* directory
> structure, they are straight copies and are only processed after being
> ordered and
> concatenated.
>
>
>
> That being said, if
> a feature with a Kconfig of the kernel has a "select UNIONFS"
> then you
> can't override it with a config/defconfig option, you need to
> patch
> the kernel.
>
> Not sure what you are saying here. If you mean that the unionfs
> kernel option is required by another selected kernel config
> option, I'm pretty sure that's not the case. I can bitbake -c
> menuconfig virtual/kernel and merely deselect the unionfs option
> and the kernel is good.
>
>
> I can't see your source tree, so it was always an option. I know it
> definitely isn't
> the case in the linux-yocto tree. But the ability to deselect it in
> menuconfig isn't
> contingent on something else not selecting it from within another Kconfig.
>
> Again, if you send me your defconfig and local.conf changes (for the
> BSP), I'll
> run a kernel configuration test and be able to easily tell you what is
> happening.
>
> Cheers,
>
> Bruce
>
>
> Brian
>
>
>
>
>
> If you send me your defconfig, I can run some test builds here.
>
> Bruce
>
>
>
>
>
> Thanks,
>
> Brian
>
>
>
>
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>
>
>
>
> --
> "Thou shalt not follow the NULL pointer, for chaos and madness await
> thee at its end"
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