[U-Boot] [PATCH 7/9] mx53loco: Add support to dynamically choose between ftd use or not

[Otavio Salvador]

On Wed, Dec 26, 2012 at 10:14 AM, Fabio Estevam <festevam at gmail.com> wrote:
> On Wed, Dec 26, 2012 at 9:31 AM, Stefano Babic <sbabic at denx.de> wrote:
>
>> Only to remark that this is the correct behavior. The kernel with fdt is
>> booted independently if this is wanted or not, but if the fdt file is
>> loaded successfully from MMC or network. This can have some drawback
>> effects if, for example, the fdt is simply stored on the TFTP server,
>> but we want to boot a kernel without DT. For example, when someone wants
>> to test both kernels or there are multiple instances of the same board
>> type (mx53loco in this case) loading from the same TFTP server.
>>
>> In your patch, the behavior depends if the fdt is simply present on the
>> media, but this does not always mean that the file must be loaded.
>> Should be not better to set variable as flag to force the desired
>> behavior and to be sure that the system does not boot in a different way
>> as the user thinks ?
>>
>> In other words, something like :
>>
>>         "if boot_fdt; then " \
>>                 "if dhcp ${ftd_addr} ${ftd_file}; then " \
>>                         "bootm ${loadaddr} - ${ftd_addr}; " \
>>                 "else " \
>>                         "echo Error: I cannot boot a DT kernel; \"
>>                 "fi; \"
>>         " else bootm; fi;\0"
>
>
> Yes, I think this is a good idea and would allow us to easily switch
> from dt to non-dt kernel during tests.

I like the idea but maybe we could have three states?

boot_fdt=yes

It'd imply force fdt and would behave as you said above;

boot_fdt=no

Would ignore the fdt completely

boot_fdt=auto

The current code, which try to load fdt and do not fail otherwise.

Comments?

--
Otavio Salvador                             O.S. Systems
E-mail: otavio at ossystems.com.br  http://www.ossystems.com.br
Mobile: +55 53 9981-7854              http://projetos.ossystems.com.br