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

[Aaron Durbin (Code Review)]

Aaron Durbin has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/35165 )

Change subject: arch/x86: Reserve some CAR memory for FSP single stack requirement
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Patch Set 9:

(1 comment)

https://review.coreboot.org/c/coreboot/+/35165/9/src/arch/x86/car.ld 
File src/arch/x86/car.ld:

https://review.coreboot.org/c/coreboot/+/35165/9/src/arch/x86/car.ld@94 
PS9, Line 94: #if CONFIG(FSP_USES_CB_STACK)
> if reviewers say we need to guard with ENV_ROMSTAGE then we could do that.

Yes, it should be guarded to be more correct. However, what matters here is the ordering. It's ok sitting here, but it can't be before _car_global_start. I believe this could also be achieved with an array:

static uint8_t fsp_heap[CONFIG_FSP_DCACHE_HEAP_SIZE] __aligned(sizeof(uint64_t);

The compiler will cull the allocation based on FSP_USES_CB_STACK Kconfig w/ garbage collection of the unused sections.