[RFC] arm64: Add support to pass earlyprintk argument via device tree

[Pranavkumar Sawargaonkar]

Hi Catalin,

On 28 May 2013 21:20, Catalin Marinas <catalin.marinas at arm.com> wrote:
> On Wed, May 22, 2013 at 11:48:33AM +0100, Pranavkumar Sawargaonkar wrote:
>> This patch adds support for defining and passing earlyprintk
>> related information i.e. device and address information via
>> device tree by adding it inside "chosen" node.
>>
>> This will help user to just specify "earlyprintk" from bootargs
>> without actually knowing the address and device to enable
>> earlyprintk.
>>
>> Mechanism:
>>
>> One can just append earlyprintk=device-type,address (same as we pass
>> through command line) in "/chosen" node to notify kernel which is the
>> earlyprintk device and what is its address.
>
> I think the idea is good but I would like to see some comments from
> people more familiar with the DT.
>
>> --- a/arch/arm64/kernel/setup.c
>> +++ b/arch/arm64/kernel/setup.c
>> @@ -60,6 +60,9 @@ EXPORT_SYMBOL(processor_id);
>>  unsigned int elf_hwcap __read_mostly;
>>  EXPORT_SYMBOL_GPL(elf_hwcap);
>>
>> +char *earlyprintk_dt_args;
>> +EXPORT_SYMBOL_GPL(earlyprintk_dt_args);
>
> Why exporting it? Would you expect this to be used from modules?

Actually i will remove it, it is not really going to be used by modules.
Also i have externed this variable(char *earlyprintk_dt_arg ) in
early_pritnk.c file
just because of not finding proper header file, really like to move
that to some header...


>
> --
> Catalin

Thanks,
Pranav