Nico Huber has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/41471 )
Change subject: soc/intel/broadwell: Mask lower 20 bits of TOLUD and TOLM in systemagent.asl ......................................................................
Patch Set 6:
(1 comment)
https://review.coreboot.org/c/coreboot/+/41471/6/src/soc/intel/broadwell/acp... File src/soc/intel/broadwell/acpi/systemagent.asl:
https://review.coreboot.org/c/coreboot/+/41471/6/src/soc/intel/broadwell/acp... PS6, Line 156: If (Local0 == Local1) {
I don't think any chipset code reserves this region. […]
The ME stolen memory is always directly below TOM and TOM is always the amount of installed memory. AFAIK, it is never mapped into the host memory space.
In the 4GiB case, it lives in DRAM at 0xfe000000..0xffffffff.
There is another inconsistency: Assuming we would have 3GiB installed, ME is 0xbe000000..0xbfffffff. If we can live with a 1GiB memory hole, TOLUD could be at 0xce000000, too. And this code here would use TOM (0xc0000000) instead. But if we'd set a 2GiB hole, TOLUD would be 0x80000000, and this code would ignore the ME range, that is still at 0xbe000000.