[U-Boot] [PATCH 03/22] Add core support for a bloblist to convey data from SPL

[Simon Glass]

Hi Andreas,

On 26 September 2018 at 21:54, Andreas Dannenberg <dannenberg at ti.com> wrote:
> Hi Simon,
> some quick comments/notes inlined...
>
> On Wed, Sep 26, 2018 at 03:55:01PM -0600, Simon Glass wrote:
>> At present there is no standard way in U-Boot to pass information from SPL
>> to U-Boot proper. But sometimes SPL wants to convey information to U-Boot
>> that U-Boot cannot easily figure out. For example, if SPL sets up SDRAM
>> then it might want to pass the size of SDRAM, or the location of each
>> bank, to U-Boot proper.
>>
>> Add a new 'bloblist' feature which provides this. A bloblist is set up in
>> the first phase of U-Boot that runs (i.e. TPL or SPL). The location of
>> this info may be in SRAM or CAR (x86 cache-as-RAM) or somewhere else.
>>
>> Information placed in this region is preserved (with a checksum) through
>> TPL and SPL and ends up in U-Boot. At this point it is copied into SDRAM
>> so it can be used after relocation.
>>
>
> Seems generally quite useful. For example on different TI platforms we
> read out various board-specific information from an EEPROM in SPL (in
> addition to DDR related stuff) which needs to be passed to U-Boot proper
> and for that we have established the concept of a "scratch pad SRAM"
> which essentially serves the same purpose but is very rudimentary for
> example with no protection against corruption whereas the bloblists can
> use CRC... very nice.

OK good. I was a bit unsure about whether CRC was worth it. But I can
see cases where something might go wrong.

Will take care of your comments, thanks.

Regards,
Simon