Rangineni Balu
Hello everybody,
We designed one custom board with TI's OMAP processor similar to beagleboard.
we registered our board and got Machine ID, even i gave wrong machine ID (i.e., i tried different .dts accidentally IDs are different in each case), my kernel is booting.
In .dts, i made this entry
model = "CDAC OMAP3 WINGZ board";
compatible = "CDAC,omap3-wingz", "ti,omap3";
I didn't do any changes to the kernel with compatible entry for "CDAC, omap3-wingz", but still kernel is booting without any problem.
What my question is
1. Is it really required to pass Machine ID as a parameter to the linux kernel while booting ?
2. How the kernel is booting even i gave "compatible" field which is not at all available as an entry in linux kernel?
Is only device tree is sufficient to boot the kernel on ARM boards?
Thanks & Regards,
Robert Nelson
On Dec 22, 2014 10:36 PM, "Rangineni Balu" <rangine...@gmail.com> wrote:
>
> Hello everybody,
>
>
> We designed one custom board with TI's OMAP processor similar to beagleboard.
> we registered our board and got Machine ID, even i gave wrong machine ID (i.e., i tried different .dts accidentally IDs are different in each case), my kernel is booting.
>
> In .dts, i made this entry
>
> model = "CDAC OMAP3 WINGZ board";
> compatible = "CDAC,omap3-wingz", "ti,omap3";
>
> I didn't do any changes to the kernel with compatible entry for "CDAC, omap3-wingz", but still kernel is booting without any problem.
>
> What my question is
> 1. Is it really required to pass Machine ID as a parameter to the linux kernel while booting ?
> 2. How the kernel is booting even i gave "compatible" field which is not at all available as an entry in linux kernel?
>
That string is used to help differentiate your board in the kernel.
Example of some pdata qwerks that use that value.
> Is only device tree is sufficient to boot the kernel on ARM boards?
>
> Thanks & Regards,
>
> --
> For more options, visit http://beagleboard.org/discuss
> ---
> You received this message because you are subscribed to the Google Groups "BeagleBoard" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to beagleboard...@googlegroups.com.
> For more options, visit https://groups.google.com/d/optout.
Rangineni Balu
On Tuesday, December 23, 2014 10:15:48 AM UTC+5:30, RobertCNelson wrote:
On Dec 22, 2014 10:36 PM, "Rangineni Balu" <rangine...@gmail.com> wrote:
>
> Hello everybody,
>
>
> We designed one custom board with TI's OMAP processor similar to beagleboard.
> we registered our board and got Machine ID, even i gave wrong machine ID (i.e., i tried different .dts accidentally IDs are different in each case), my kernel is booting.
>
> In .dts, i made this entry
>
> model = "CDAC OMAP3 WINGZ board";
> compatible = "CDAC,omap3-wingz", "ti,omap3";
>
> I didn't do any changes to the kernel with compatible entry for "CDAC, omap3-wingz", but still kernel is booting without any problem.
>
> What my question is
> 1. Is it really required to pass Machine ID as a parameter to the linux kernel while booting ?
> 2. How the kernel is booting even i gave "compatible" field which is not at all available as an entry in linux kernel?
>That string is used to help differentiate your board in the kernel.
Example of some pdata qwerks that use that value.
/*
* Few boards still need to initialize some legacy devices with
* platform data until the drivers support device tree. Robert Nelson
>
> /*
> * Few boards still need to initialize some legacy devices with
> * platform data until the drivers support device tree.
>
> */
>
> From the above comment, i think it is not required to add compatible field
> for my board in kernel. Since my board is based on beagleboard, there is no
> legacy devices for beagleboard which required paltform data. Am i right?
>
> If i gave any name in the compatible field in .dts it doesn't matter for
> kernel i think.
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/devicetree/bindings/arm/omap/omap.txt
> What about the Machine ID ?
Regards,
--
Robert Nelson
http://www.rcn-ee.com/