[coreboot] unrv2b delay (v2)

[Marc Jones]

Arne Georg Gleditsch wrote:
> Peter Stuge <peter at stuge.se> writes:
>> Arne Georg Gleditsch wrote:
>>> The unrv2b uncompression algorithm appears to behave very badly in
>>> the absence of a proper cache.
>> But why does this improve when the algorithm runs out of RAM?
>>
>> Could ROM accesses be a factor?
> 
> Yes, at least in the sense that running from ROM means we're running
> from an uncached memory region.  I assume you'd notice much the same
> running from uncached DRAM as well.  copy_and_run is one of the few
> things that run after cache-as-ram has been disabled but before our code
> has been copied to proper DRAM, so it is especially sensitive regarding
> code footprint.
> 

I have thought about this a while back and have wanted to make a change. 
Disabling CAR should fixup the stack etc but for performance reasons we 
should setup/leave ROM and RAM caching enabled on the BSP. If you are 
interested in looking at that I think it would be great.

Marc


-- 
Marc Jones
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