[coreboot-gerrit] Change in coreboot[master]: arch/x86: Reserve some CAR memory for FSP single stack requirement

[Subrata Banik (Code Review)]

Hello Kyösti Mälkki, Aaron Durbin, Patrick Rudolph, Nathaniel L Desimone, Angel Pons, Aamir Bohra, Kane Chen, build bot (Jenkins), Furquan Shaikh, Meera Ravindranath, Usha P, Tim Wawrzynczak, Philipp Deppenwiese, V Sowmya,

I'd like you to reexamine a change. Please visit

https://review.coreboot.org/c/coreboot/+/35165

to look at the new patch set (#4).

Change subject: arch/x86: Reserve some CAR memory for FSP single stack requirement
......................................................................

arch/x86: Reserve some CAR memory for FSP single stack requirement

From FSP2.1 onwards stack and heap requirement has changed
(For documentation on this feature, please see page 25 of the
FSP v2.1 specification (https://cdrdv2.intel.com/v1/dl/getContent/611786))

arch_upd->StackBase will refer as Heap Start for HOB and arch_upd->StackSize
will be heap size.

As FSP and coreboot will same stack hence FSP doesn't need dedicated
UPD to pass stack start information.

But FSP might need to know where to keep HOB heap and for the same purpose
it usage StackBase and StackSize UPDs (names are confusing!)

Proposed to reserve a small region above _car_global_end with platform
given DACHE_BSP_HEAP_SIZE for FSP to keep HOB heap.

+--------------+ _car_region_end
                 |              |
 FSP stack end   +--------------+ _car_heap_end
                 |heap          |
 FSP heap base   +--------------+ _car_heap_start/_car_global_end
                 |car global    |
                 +--------------+ _car_global_start
                 +--------------+ _car_relocatable_data_start
 FSP stack end   +--------------+ _car_stack_end
                 |              |
                 +--------------+
                 |stack_guard   |
 FSP stack base  +--------------+ _car_stack_start
                 |vboot         |
                 +--------------+ _car_region_start

BUG=b:140268415

Change-Id: I943eff1225b976dc4440a6ca6d02ceea378319f8
Signed-off-by: Subrata Banik 
---
M src/arch/x86/car.ld
M src/arch/x86/include/arch/symbols.h
M src/cpu/Kconfig
M src/drivers/intel/fsp2_0/memory_init.c
4 files changed, 46 insertions(+), 2 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/65/35165/4