[U-Boot] [PATCH 1/2] efi_loader: Pass fdt address directly to bootefi cmd

[Alexander Graf]

On 04/14/2016 01:20 AM, Stephen Warren wrote:
> On 04/13/2016 03:22 PM, Alexander Graf wrote:
>> The bootefi cmd today fetches its device tree pointer from either the
>> location appointed by "fdt addr" with a fallback to the U-Boot control
>> fdt.
>>
>> This integration is unusual for U-Boot and diverges from the way we
>> usually handle parameters to boot commands. So let's pass the fdt
>> directly into the bootefi command instead and move the control fdt
>> logic into the distro boot script.
>
>> diff --git a/cmd/bootefi.c b/cmd/bootefi.c
>
>> @@ -155,13 +154,7 @@ static unsigned long do_bootefi_exec(void *efi)
>>        */
>>       efi_save_gd();
>>
>> -    /* Update system table to point to our currently loaded FDT */
>> -
>> -    /* Fall back to included fdt if none was manually loaded */
>> -    if (!fdt && gd->fdt_blob)
>> -        fdt = (void *)gd->fdt_blob;
>> -
>> -    if (fdt) {
>> +    if (fdt && !fdt_check_header(fdt)) {
>>           /* Prepare fdt for payload */
>>           fdt = copy_fdt(fdt);
>>
>> @@ -185,7 +178,7 @@ static unsigned long do_bootefi_exec(void *efi)
>>           efi_add_memory_map(fdt_start, fdt_pages,
>>                      EFI_BOOT_SERVICES_DATA, true);
>>       } else {
>> -        printf("WARNING: No device tree loaded, expect boot to 
>> fail\n");
>> +        printf("WARNING: Invalid device tree, expect boot to fail\n");
>
> I'm not familiar with this code, so I'm not really sure what the 
> implication of this if/else is.
>
> Still, this looks like it's a move in the right direction. I do agree 
> the FDT address parameter likely should be optional, and if not 
> specified by the user default to whatever other bootz/booti default 
> too (I suspect $fdt_addr_r).

So what bootz/booti do is to either take the 3rd parameter as fdt, have 
the fdt included in the image you boot (FIT or legacy combined images) 
and when it's loaded, they call

   set_working_fdt_addr((ulong)images.ft_addr);

which basically does the same as my previous "fdt addr". But I see no 
fallback to $fdt_addr_r. It just doesn't use an fdt if no fdt parameter 
/ fit image was provided.


Alex