How to pass information from the bootloader to the kernel ?

How to pass information from the bootloader to the kernel ?

[Laurent Pinchart]

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Hi everybody,

I need to pass a limited amount of information from the boot loader to the 
Linux kernel, such as the boot mode chosen by the user or the last boot 
reason (power up, reset, watchdog, ...).

What is the best way to pass that kind of information from the boot loader to 
the kernel ? Should I use the device tree ?

I thought about populating the chosen node with the data I need. This could 
make sense for the boot mode, but I feel like I would abuse the chosen node 
if I used it to pass other "non user chosen" information.

Best regards,

-- 
Laurent Pinchart
CSE Semaphore Belgium

Chaussee de Bruxelles, 732A
B-1410 Waterloo
Belgium

T +32 (2) 387 42 59
F +32 (2) 387 42 75

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Re: How to pass information from the bootloader to the kernel ?

[Grant Likely]

On Thu, Apr 10, 2008 at 9:50 AM, Laurent Pinchart
<laurentp@cse-semaphore.com> wrote:
> Hi everybody,
>
>  I need to pass a limited amount of information from the boot loader to the
>  Linux kernel, such as the boot mode chosen by the user or the last boot
>  reason (power up, reset, watchdog, ...).
>
>  What is the best way to pass that kind of information from the boot loader to
>  the kernel ? Should I use the device tree ?
>
>  I thought about populating the chosen node with the data I need. This could
>  make sense for the boot mode, but I feel like I would abuse the chosen node
>  if I used it to pass other "non user chosen" information.

Using the chosen node should be fine.  Just prefix your new properties
with your company name or something so that you don't get namespace
collisions.  However, whatever you do; document it first and post your
documentation to the mailing list for review.

Cheers,
g.


>
>  Best regards,
>
>  --
>  Laurent Pinchart
>  CSE Semaphore Belgium
>
>  Chaussee de Bruxelles, 732A
>  B-1410 Waterloo
>  Belgium
>
>  T +32 (2) 387 42 59
>  F +32 (2) 387 42 75
>
> _______________________________________________
>  Linuxppc-dev mailing list
>  Linuxppc-dev@ozlabs.org
>  https://ozlabs.org/mailman/listinfo/linuxppc-dev
>



-- 
Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.

Re: How to pass information from the bootloader to the kernel ?

[Kumar Gala]

On Apr 10, 2008, at 10:50 AM, Laurent Pinchart wrote:
> Hi everybody,
>
> I need to pass a limited amount of information from the boot loader  
> to the
> Linux kernel, such as the boot mode chosen by the user or the last  
> boot
> reason (power up, reset, watchdog, ...).
>
> What is the best way to pass that kind of information from the boot  
> loader to
> the kernel ? Should I use the device tree ?
>
> I thought about populating the chosen node with the data I need.  
> This could
> make sense for the boot mode, but I feel like I would abuse the  
> chosen node
> if I used it to pass other "non user chosen" information.

using chosen is fine, just remember to prefix properties with some  
vendor prefix.

- k