[Buildroot] rebuild dtb?

[Buildroot] rebuild dtb?

[Steve deRosier]

Hi all,

I was wondering if there was a make target similar to linux-rebuild that
would force a rebuild of the dtb?

We're using an override to allow a live source tree of the kernel for our
current kernel work. I'm doing some work on the device trees and I'd really
like a way to just rebuild the dtb and attach it to the kernel image.
 Alternately I've been using linux-rebuild and can continue to do so.

However, I've noticed an issue with linux-rebuild with re: to the device
tree.  I have to make a modification to a kernel source (doesn't seem to
matter) to get it to rebuild + cat the dtb with the kernel.  Here's what I
see:

I modify the dts only, then do a `make O=<my output dir> linux-rebuild` and
it does rebuild the dtb, but when I load the kernel on my target, my dts
changes don't take effect.  It doesn't look like it cat'd the dtb with the
kernel and created the image properly.

I modify the dts, and I make a trivial change to a kernel file (in this
case arch/arm/mach-at91/pm.c), it rebuilds the file, the dtb, and
successfully does the cat of the kernel + dtb to make a new image.  When I
deploy it on my target and test, my dts changes are evident.

Thoughts/help?

Thanks,
- Steve
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[Buildroot] rebuild dtb?

[Arnout Vandecappelle]

On 07/08/13 01:22, Steve deRosier wrote:
> Hi all,
>
> I was wondering if there was a make target similar to linux-rebuild that
> would force a rebuild of the dtb?
>
> We're using an override to allow a live source tree of the kernel for our
> current kernel work. I'm doing some work on the device trees and I'd
> really like a way to just rebuild the dtb and attach it to the kernel
> image.  Alternately I've been using linux-rebuild and can continue to do so.
>
> However, I've noticed an issue with linux-rebuild with re: to the device
> tree.  I have to make a modification to a kernel source (doesn't seem to
> matter) to get it to rebuild + cat the dtb with the kernel.  Here's what
> I see:
>
> I modify the dts only, then do a `make O=<my output dir> linux-rebuild`
> and it does rebuild the dtb, but when I load the kernel on my target, my
> dts changes don't take effect.  It doesn't look like it cat'd the dtb
> with the kernel and created the image properly.
>
> I modify the dts, and I make a trivial change to a kernel file (in this
> case arch/arm/mach-at91/pm.c), it rebuilds the file, the dtb, and
> successfully does the cat of the kernel + dtb to make a new image.  When
> I deploy it on my target and test, my dts changes are evident.
>
> Thoughts/help?

  Seems like an issue with the kernel build system, not buildroot. If the 
.dtb is not rebuilt in the output directory 
(output/build/linux-*/arch/arm/boot/dts), then it's a kbuild problem. If 
the .dtb is rebuilt but buildroot doesn't append it to the image, then 
it's a buildroot problem.

  Regards,
  Arnout


-- 
Arnout Vandecappelle                          arnout at mind be
Senior Embedded Software Architect            +32-16-286500
Essensium/Mind                                http://www.mind.be
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