[U-Boot] [PATCH V2] add README.distro file

[Stephen Warren]

On 12/28/2014 03:09 AM, Ian Campbell wrote:
> On Mon, 2014-12-22 at 13:46 -0700, Stephen Warren wrote:
>> [...]
>> +
>> +The U-Boot "syslinux" and "pxe boot" commands require a number of environment
>> +variables be set. Default values for these variables are often hard-coded into
>> +CONFIG_EXTRA_ENV_SETTINGS in the board's U-Boot configuration file, so that
>> +the user doesn't have to configure them.
>> +
>> +fdt_addr:
>> +
>> +  Optional. If specified a dtb to boot the system must be available at the
>> +  given address.
>> +
>> +fdt_addr_r:
>> +
>> +  Mandatory.
>
> Isn't this one only mandatory if ${fdt_addr} is not given?

Yes. I guess it's mandatory for at least one of fdt_addr or fdt_addr_r 
to be set, according to common/cmd_pxe.c:

> 	 * fdt usage is optional:
> 	 * It handles the following scenarios. All scenarios are exclusive
> 	 *
> 	 * Scenario 1: If fdt_addr_r specified and "fdt" label is defined in
> 	 * pxe file, retrieve fdt blob from server. Pass fdt_addr_r to bootm,
> 	 * and adjust argc appropriately.
> 	 *
> 	 * Scenario 2: If there is an fdt_addr specified, pass it along to
> 	 * bootm, and adjust argc appropriately.
> 	 *
> 	 * Scenario 3: fdt blob is not available.

So, I'll need to reword that a little to make that clear.