[coreboot] removing bounce buffers

Nico Huber nico.h at gmx.de
Wed Oct 3 00:03:27 CEST 2018


On 10/2/18 10:16 PM, ron minnich wrote:
> we are at long last removing bounce buffers from selfboot.
> https://review.coreboot.org/c/coreboot/+/28647
> 
> This greatly simplifies the code and there are almost no platforms left
> that need them. Here are the ones that seem to:
> 
> src/northbridge/amd/amdfam10/Kconfig
> src/northbridge/amd/lx/Kconfig
> src/northbridge/via/vx900/Kconfig
> src/soc/intel/fsp_baytrail/Kconfig
> src/soc/intel/fsp_broadwell_de/Kconfig

Out of curiosity why this hits some but not all FSP1.0 platforms I
checked the git history. I couldn't find an explanation why fsp_rangeley
and fsp_sandybridge were skipped in 7904e72. Maybe they were just over-
looked?

> 
> For these boards, I made the following change:
> "For these five boards we change CONFIG_RAMBASE from 0x100000 (the
> value needed in 1999 for the 32-bit Linux kernel, the original ramstage)
> to 0x3d00000 (64 MiB - 2 MiB) which will put the non-relocatable x86

nb. that's -3MiB

> ramstage out of the way of any reasonable payload until we can
> get rid of it for good."

Not sure about this, but a wild guess: If you build a libpayload payload
with a huge heap (part of .bss, IIRC), you might easily reach this area.
Not that I would care (don't own any of the affected platforms), but if
this is the case, it might be a problem for other people.

Nico



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