[U-Boot] [RFC PATCH] common: fdt_support: Remove fdt_add_mem_rsv in fdt_shrink_to_minimum

[keerthy]

On 4/12/2019 7:39 AM, Simon Glass wrote:
> Hi Keerthy,
> 
> On Wed, 30 Jan 2019 at 06:41, Keerthy <j-keerthy at ti.com> wrote:
>>
>> With introduction of commit:
>>
>> a156c47e39ad: tftp: prevent overwriting reserved memory
>>
>> tftp with loadaddr is failing for Images of the size bigger than SPL.
>> The issue is that SPL image is located at bootaddr
>> and dtb is allocated at bootaddr + spl_size.
>>
>> The region where dtb is present is marked reserved.
>>
>> So when the tftp tries to load the Image it tries to find
>> a location from loadaddr to the first reserved memory region
>> which is the dtb base address. The max_size obtained is pretty
>> less and hence tftp fails with the below error:
>>
>> TFTP error: trying to overwrite reserved memory...
> 
> I don't quite get this. Are you saying that we load U-Boot to
> loadaddr, overwriting the SPL DT?

Simon,

No. Basically when we try to load kernel to bootaddr using tftp there is 
dtb present at bootaddr+spl_size and its marked as reserved. So TFTP 
fails. IMHO post relocation it should not be marked as reserved. 
Basically we will never be able to find enough space between bootaddr 
and dtb address for us to fit kernel Image and tftp will always fail for 
bootaddr.

Hope i am clear now.

Regards,
Keerthy
> 
> Simon Goldschmidt, any thoughts?
> 
> Regards,
> Simon
> 
> 
>>
>> Signed-off-by: Keerthy <j-keerthy at ti.com>
>> ---
>>
>> I am sure there are better solutions so just wanted to know
>> if there is one.
>>
>>   common/fdt_support.c | 5 -----
>>   1 file changed, 5 deletions(-)
>>
>> diff --git a/common/fdt_support.c b/common/fdt_support.c
>> index 42583e3ed8..2bb101e56e 100644
>> --- a/common/fdt_support.c
>> +++ b/common/fdt_support.c
>> @@ -633,11 +633,6 @@ int fdt_shrink_to_minimum(void *blob, uint extrasize)
>>          /* Change the fdt header to reflect the correct size */
>>          fdt_set_totalsize(blob, actualsize);
>>
>> -       /* Add the new reservation */
>> -       ret = fdt_add_mem_rsv(blob, map_to_sysmem(blob), actualsize);
>> -       if (ret < 0)
>> -               return ret;
>> -
>>          return actualsize;
>>   }
>>
>> --
>> 2.17.1
>>