[coreboot] CONFIG_CBFS_SIZE vs CONFIG_ROM_SIZE

[Nico Huber]

On 23.05.2017 18:49, Gailu Singh wrote:
> Hi Experts,
> 
> If we use CBFS_SIZE to be same as ROM_SIZE on our apollolake board grub
> fails to load grub.cfg located in CBFS. Based on experiments we found that
> grub.cfg is loaded correctly if we keep minimum difference of 64KB between
> CBFS_SIZE and ROM_SIZE if we reduce it to less that 64KB problem happens.
> 
> Can someone please explain the behavior and if it is expected behavior or a
> bug?

Setting both the same seems very wrong to me for Apollo Lake. ROM_SIZE
is supposed to be the full size of the flash chip. That chip is shared
by SoC configuration, blobs and the BIOS/coreboot. coreboot will reside
in the "BIOS" region of the chip, CBFS_SIZE should be at most the size
of that region.

Hope that helps,
Nico