[U-Boot] [PATCH 1/3] powerpc/p1010rdb: SECURE BOOT- define CONFIG_SYS_RAMBOOT for NAND boot

[York Sun]

On 03/06/2014 01:24 AM, Bansal Aneesh-B39320 wrote:
>> -----Original Message-----
>> From: Wood Scott-B07421
>> Sent: Wednesday, March 05, 2014 11:30 PM
>> To: Bansal Aneesh-B39320
>> Cc: Sun York-R58495; Wolfgang Denk; u-boot at lists.denx.de; Gupta
>> Ruchika-R66431
>> Subject: Re: [U-Boot] [PATCH 1/3] powerpc/p1010rdb: SECURE BOOT-
>> define CONFIG_SYS_RAMBOOT for NAND boot
>>
>> On Tue, 2014-03-04 at 23:30 -0600, Bansal Aneesh-B39320 wrote:
>>> Yes, in case of secure boot from NAND, the DRAM is initialized by
>> the
>>> BootROM and complete u-boot image is copied from NAND to DRAM by the
>> BootROM.
>>> So, it should be called RAMBOOT.
>>
>> DRAM or SRAM?  Having ROM initialize DDR is a bit scary.
>>
>> -Scott
>>
> It can be either DDR or SRAM. It is not hardcoded in BootROM to initialize DDR.
> This depends on the config words (CF_WORDS) in the CF_HEADER.
> The Boot ROM code parses the config words and programs the addresses with data values
> accordingly. The user may opt to initialize DDR and get the image copied onto DDR or 
> configure CPC as SRAM and get the Image copied onto SRAM.
> On 1010, the CPC size is not big enough to accommodate the U-boot image.
> So, currently the CF_WORDS are for DDR to be initialized and copy the image on DDR.
> 

Does it use similar technique like PBI to initialize DDR? If so, it has static
settings which cannot adapt to various speeds. That's OK if you have to do so.
In this case, your u-boot image is a RAMBOOT. I suggest you to update the
subject to avoid mixing NAND boot with RAMBOOT, and add comment or commit
message to explain the image is loaded into DDR and run directly from there.

York