embedding dtb file into kernel

embedding dtb file into kernel

[K Richard Pixley]

I'm having trouble figuring out how to embed a dtb file into my kernel.  
I'm thinking that there should be a standard, architecture independent 
facility for this akin to initramfs, yes?

Could someone please either point me to the standard facility, relevant 
doc, a currently building board that uses the standard facility, or 
outline what needs to be done to do this with a new board?

If it matters, (I can't think why it would), I'm working with powerpc on 
a 3.10 kernel.  But if there are better facilities in other versions I'd 
appreciate hearing about that too.

Thank you in advance.

--rich

Re: embedding dtb file into kernel

[Tim Bird]

On 02/12/2015 11:33 AM, K Richard Pixley wrote:
> I'm having trouble figuring out how to embed a dtb file into my kernel.  
> I'm thinking that there should be a standard, architecture independent 
> facility for this akin to initramfs, yes?
> 
> Could someone please either point me to the standard facility, relevant 
> doc, a currently building board that uses the standard facility, or 
> outline what needs to be done to do this with a new board?
> 
> If it matters, (I can't think why it would), I'm working with powerpc on 
> a 3.10 kernel.  But if there are better facilities in other versions I'd 
> appreciate hearing about that too.

The normal method is just to cat the two files together, like so:
 $ cat zImage <filename>.dtb > zImage_w_dtb

See https://community.freescale.com/thread/315543 for one example, on ARM.
I'm not sure what the status is for appended DTBs on powerpc, but it's
easy enough you can just try it and see what happens.
 -- Tim

Re: embedding dtb file into kernel

[K Richard Pixley]

On 2/12/15 14:01 , Tim Bird wrote:
> On 02/12/2015 11:33 AM, K Richard Pixley wrote:
>> I'm having trouble figuring out how to embed a dtb file into my kernel.
>> I'm thinking that there should be a standard, architecture independent
>> facility for this akin to initramfs, yes?
>>
>> Could someone please either point me to the standard facility, relevant
>> doc, a currently building board that uses the standard facility, or
>> outline what needs to be done to do this with a new board?
>>
>> If it matters, (I can't think why it would), I'm working with powerpc on
>> a 3.10 kernel.  But if there are better facilities in other versions I'd
>> appreciate hearing about that too.
> The normal method is just to cat the two files together, like so:
>   $ cat zImage <filename>.dtb > zImage_w_dtb
>
> See https://community.freescale.com/thread/315543 for one example, on ARM.
> I'm not sure what the status is for appended DTBs on powerpc, but it's
> easy enough you can just try it and see what happens.
>   -- Tim

Thanks!

How do I tell the kernel where to find that dtb?  Is there a relevant 
config option?

--rich

Re: embedding dtb file into kernel

[Tim Bird]

On 02/12/2015 02:30 PM, K Richard Pixley wrote:
> On 2/12/15 14:01 , Tim Bird wrote:
>> On 02/12/2015 11:33 AM, K Richard Pixley wrote:
>>> I'm having trouble figuring out how to embed a dtb file into my kernel.
>>> I'm thinking that there should be a standard, architecture independent
>>> facility for this akin to initramfs, yes?
>>>
>>> Could someone please either point me to the standard facility, relevant
>>> doc, a currently building board that uses the standard facility, or
>>> outline what needs to be done to do this with a new board?
>>>
>>> If it matters, (I can't think why it would), I'm working with powerpc on
>>> a 3.10 kernel.  But if there are better facilities in other versions I'd
>>> appreciate hearing about that too.
>> The normal method is just to cat the two files together, like so:
>>   $ cat zImage <filename>.dtb > zImage_w_dtb
>>
>> See https://community.freescale.com/thread/315543 for one example, on ARM.
>> I'm not sure what the status is for appended DTBs on powerpc, but it's
>> easy enough you can just try it and see what happens.
>>   -- Tim
> 
> Thanks!
> 
> How do I tell the kernel where to find that dtb?  Is there a relevant 
> config option?

Usually you make the dtb from sources in the kernel.
I don't know how it works on powerpc, but on arm, the .dts
files are located in arch/arm/boot/dts, and you would make
the dtb for the corresponding "foo.dts" source
by typing:
$ make foo.dtb

   -- Tim

Re: embedding dtb file into kernel

[Rob Landley]

On 02/12/2015 06:56 PM, Tim Bird wrote:
> 
> 
> On 02/12/2015 02:30 PM, K Richard Pixley wrote:
>> On 2/12/15 14:01 , Tim Bird wrote:
>>> On 02/12/2015 11:33 AM, K Richard Pixley wrote:
>>>> I'm having trouble figuring out how to embed a dtb file into my kernel.
>>>> I'm thinking that there should be a standard, architecture independent
>>>> facility for this akin to initramfs, yes?
>>>>
>>>> Could someone please either point me to the standard facility, relevant
>>>> doc, a currently building board that uses the standard facility, or
>>>> outline what needs to be done to do this with a new board?
>>>>
>>>> If it matters, (I can't think why it would), I'm working with powerpc on
>>>> a 3.10 kernel.  But if there are better facilities in other versions I'd
>>>> appreciate hearing about that too.
>>> The normal method is just to cat the two files together, like so:
>>>   $ cat zImage <filename>.dtb > zImage_w_dtb
>>>
>>> See https://community.freescale.com/thread/315543 for one example, on ARM.
>>> I'm not sure what the status is for appended DTBs on powerpc, but it's
>>> easy enough you can just try it and see what happens.
>>>   -- Tim
>>
>> Thanks!
>>
>> How do I tell the kernel where to find that dtb?  Is there a relevant 
>> config option?
> 
> Usually you make the dtb from sources in the kernel.
> I don't know how it works on powerpc, but on arm, the .dts
> files are located in arch/arm/boot/dts, and you would make
> the dtb for the corresponding "foo.dts" source
> by typing:
> $ make foo.dtb

It's probably somewhere in:

https://www.kernel.org/doc/Documentation/devicetree/booting-without-of.txt

Rob

Re: embedding dtb file into kernel

[Hugh Blemings]

On 13/02/2015 17:10, Rob Landley wrote:
> On 02/12/2015 06:56 PM, Tim Bird wrote:
>>
>>
>> On 02/12/2015 02:30 PM, K Richard Pixley wrote:
>>> On 2/12/15 14:01 , Tim Bird wrote:
>>>> On 02/12/2015 11:33 AM, K Richard Pixley wrote:
>>>>> I'm having trouble figuring out how to embed a dtb file into my kernel.
>>>>> I'm thinking that there should be a standard, architecture independent
>>>>> facility for this akin to initramfs, yes?
>>>>>
>>>>> Could someone please either point me to the standard facility, relevant
>>>>> doc, a currently building board that uses the standard facility, or
>>>>> outline what needs to be done to do this with a new board?
>>>>>
>>>>> If it matters, (I can't think why it would), I'm working with powerpc on
>>>>> a 3.10 kernel.  But if there are better facilities in other versions I'd
>>>>> appreciate hearing about that too.
>>>> The normal method is just to cat the two files together, like so:
>>>>    $ cat zImage <filename>.dtb > zImage_w_dtb
>>>>
>>>> See https://community.freescale.com/thread/315543 for one example, on ARM.
>>>> I'm not sure what the status is for appended DTBs on powerpc, but it's
>>>> easy enough you can just try it and see what happens.
>>>>    -- Tim
>>>
>>> Thanks!
>>>
>>> How do I tell the kernel where to find that dtb?  Is there a relevant
>>> config option?
>>
>> Usually you make the dtb from sources in the kernel.
>> I don't know how it works on powerpc, but on arm, the .dts
>> files are located in arch/arm/boot/dts, and you would make
>> the dtb for the corresponding "foo.dts" source
>> by typing:
>> $ make foo.dtb
>
> It's probably somewhere in:
>
> https://www.kernel.org/doc/Documentation/devicetree/booting-without-of.txt

Worth pointing out the folk over in linuxppc-dev are usually pretty 
friendly, may be able to help out with this too. 
https://lists.ozlabs.org/listinfo/linuxppc-dev

Cheers,
Hugh

Re: embedding dtb file into kernel

[Sam Protsenko]

On Thu, Feb 12, 2015 at 9:33 PM, K Richard Pixley
<rpixley@graphitesystems.com> wrote:
> I'm having trouble figuring out how to embed a dtb file into my kernel.  I'm
> thinking that there should be a standard, architecture independent facility
> for this akin to initramfs, yes?
>
> Could someone please either point me to the standard facility, relevant doc,
> a currently building board that uses the standard facility, or outline what
> needs to be done to do this with a new board?
>
> If it matters, (I can't think why it would), I'm working with powerpc on a
> 3.10 kernel.  But if there are better facilities in other versions I'd
> appreciate hearing about that too.
>
> Thank you in advance.
>
> --rich
> --
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Look into Documentation/powerpc/bootwrapper.txt.
It reveals that there is "wrapper" script which does the trick and
this script should be used
via Makefile. Both "wrapper" script and Makefile resides in
arch/powerpc/boot/ directory.
I think you can figure out how to use it properly from that documentation.