[S] Change in coreboot[main]: drivers/intel/fsp: Work around multi socket Xeon-SP pipe init bug

[Shuo Liu (Code Review)]

Attention is currently required from: Andrey Petrov, Arthur Heymans, Chen, Gang C, Christian Walter, Jincheng Li, Johnny Lin, Jérémy Compostella, Lean Sheng Tan, Nico Huber, Patrick Rudolph, Paul Menzel, Ronak Kanabar, Tim Chu.

Shuo Liu has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/80579?usp=email )

Change subject: drivers/intel/fsp: Work around multi socket Xeon-SP pipe init bug
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Patch Set 4:

(4 comments)

Patchset:

PS4: 
Tested in SPR 1S system and failed to boot. Found some places needing to be revised. Our SPR 2S system is not available recent days. Maybe Patrick could help to test on his machine.

File src/arch/x86/car.ld:

https://review.coreboot.org/c/coreboot/+/80579/comment/547ae76b_5ef28c37 :
PS4, Line 15: 
To be simple, maybe we could use REGION(fspm_heap ...) here and discard the .car.fspm_heap declaration later. REGION will declare the same set of linker absolute symbols.

https://review.coreboot.org/c/coreboot/+/80579/comment/55a77496_04f3c4b1 :
PS4, Line 118: _fspm_heap = .;
Need to use ABSOLUTE(.) to make sure the symbol value is always a correct constant

File src/drivers/intel/fsp2_0/memory_init.c:

https://review.coreboot.org/c/coreboot/+/80579/comment/30df41fa_d9d92690 :
PS4, Line 175: 		extern char *_fspm_heap;
Need to use extern car _fspm_heap[] instead to make sure the symbol is instantiated as an immediate number in asm.