[U-Boot] minnowboard max .dtb file

[U-Boot] minnowboard max .dtb file

[Beaman, Thomas]

Hi Bin,

I see that you have created a .dts file for the minnowboard max in arch/x86/dts/minnow.dts  What I cannot see is how to load and use this file. I cannot find any example of its use.  In the RAMBOOT line zboot is used to load the kernel and ramdisk, but it does not take a parameter for an FDT file. Any insight you can provide on the use of a dtb file for the minnow max would be appreciated.

Thanks,
Tom

[U-Boot] minnowboard max .dtb file

[Bin Meng]

+Simon

Hi Tom,

On Wed, Jun 24, 2015 at 10:38 PM, Beaman, Thomas
<Thomas.Beaman@xerox.com> wrote:
> Hi Bin,
>
> I see that you have created a .dts file for the minnowboard max in arch/x86/dts/minnow.dts  What I cannot see is how to load and use this file. I cannot find any example of its use.

You can read doc/README.fdt-control to understand how dts is compiled
to dtb and used by U-Boot.

> In the RAMBOOT line zboot is used to load the kernel and ramdisk, but it does not take a parameter for an FDT file. Any insight you can provide on the use of a dtb file for the minnow max would be appreciated.

zboot is used to load linux kernel while a typical x86 kernel does not
require dtb (although linux x86 supports device tree as its
configuration source). And you seems to be confused by dtbs. The dtb
U-Boot is using is not the same one passed to linux kernel on
arm/powerpc.

Regards,
Bin

[U-Boot] minnowboard max .dtb file

[Beaman, Thomas]

Hi Bin,

Thanks you for the quick response, my responses are embedded below

On Wed, Jun 24, 2015 at 10:38 PM, Beaman, Thomas <Thomas.Beaman@xerox.com> wrote:
>> Hi Bin,
>>
>> I see that you have created a .dts file for the minnowboard max in arch/x86/dts/minnow.dts  What I cannot see is how to load and use this file. I cannot find any example of its use.

> You can read doc/README.fdt-control to understand how dts is compiled to dtb and used by U-Boot.

I am ok with the compiling part , and this readme does explain the U-Boot FDT usage. Thanks for pointing this out.

>> In the RAMBOOT line zboot is used to load the kernel and ramdisk, but it does not take a parameter for an FDT file. Any insight you can provide on the use of a dtb file for the minnow max would be appreciated.

> zboot is used to load linux kernel while a typical x86 kernel does not require dtb (although linux x86 supports device tree as its configuration source). And you seems to be confused by dtbs. The dtb U-Boot is using is not the same one passed to linux kernel on arm/powerpc.

You are correct I was confused about the usage of the dtb file in U-Boot.  I know it is probably outside the scope of U-Boot, but do you have any pointers to info on linux x86 kernel usage of a FDT (dtb) file for configuration source

Regards,
Tom

[U-Boot] minnowboard max .dtb file

[Bin Meng]

Hi Tom,

On Wed, Jun 24, 2015 at 11:19 PM, Beaman, Thomas
<Thomas.Beaman@xerox.com> wrote:
> Hi Bin,
>
> Thanks you for the quick response, my responses are embedded below
>
> On Wed, Jun 24, 2015 at 10:38 PM, Beaman, Thomas <Thomas.Beaman@xerox.com> wrote:
>>> Hi Bin,
>>>
>>> I see that you have created a .dts file for the minnowboard max in arch/x86/dts/minnow.dts  What I cannot see is how to load and use this file. I cannot find any example of its use.
>
>> You can read doc/README.fdt-control to understand how dts is compiled to dtb and used by U-Boot.
>
> I am ok with the compiling part , and this readme does explain the U-Boot FDT usage. Thanks for pointing this out.
>
>>> In the RAMBOOT line zboot is used to load the kernel and ramdisk, but it does not take a parameter for an FDT file. Any insight you can provide on the use of a dtb file for the minnow max would be appreciated.
>
>> zboot is used to load linux kernel while a typical x86 kernel does not require dtb (although linux x86 supports device tree as its configuration source). And you seems to be confused by dtbs. The dtb U-Boot is using is not the same one passed to linux kernel on arm/powerpc.
>
> You are correct I was confused about the usage of the dtb file in U-Boot.  I know it is probably outside the scope of U-Boot, but do you have any pointers to info on linux x86 kernel usage of a FDT (dtb) file for configuration source

Please check kernel documentation booting-without-of.txt. But I am
wondering why do you want to use FDT on Linux x86 kernel?

Regards,
Bin

[U-Boot] minnowboard max .dtb file

[Beaman, Thomas]

Hi Bin,

>> You are correct I was confused about the usage of the dtb file in 
>> U-Boot.  I know it is probably outside the scope of U-Boot, but do you 
>> have any pointers to info on linux x86 kernel usage of a FDT (dtb) 
>> file for configuration source

> Please check kernel documentation booting-without-of.txt. But I am wondering why do you want to use FDT on Linux x86 kernel?

I will look at this document in more detail.  I currently do PowerPC work and like the flexibility of the FDT files.
I would like to apply similar flexibility to my current x86 work. Do you have any Pros or Cons about doing this for x86 embedded work ?  

Regards,
Tom

[U-Boot] minnowboard max .dtb file

[Bin Meng]

Hi Tom,

On Wed, Jun 24, 2015 at 11:50 PM, Beaman, Thomas
<Thomas.Beaman@xerox.com> wrote:
>
> Hi Bin,
>
>>> You are correct I was confused about the usage of the dtb file in
>>> U-Boot.  I know it is probably outside the scope of U-Boot, but do you
>>> have any pointers to info on linux x86 kernel usage of a FDT (dtb)
>>> file for configuration source
>
>> Please check kernel documentation booting-without-of.txt. But I am wondering why do you want to use FDT on Linux x86 kernel?
>
> I will look at this document in more detail.  I currently do PowerPC work and like the flexibility of the FDT files.
> I would like to apply similar flexibility to my current x86 work. Do you have any Pros or Cons about doing this for x86 embedded work ?
>

Linux x86 kernel has various sources for it to configure the hardware,
via configuration tables like PIRQ/SFI/MP/ACPI and device tree. You
can describe all configuration in the device tree without using other
mechanism. There is no such limitation as long as you come up with a
proper binding for Linux kernel to use.

Regards,
Bin