Julius Werner has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/31978 )
Change subject: Move calls to quick_ram_check() before CBMEM init ......................................................................
Patch Set 4:
Welp, that was a nasty rabbit hole. It turns out that the sudden jump in size has nothing to do with the actual code you're adding, but is triggered by an Arm errata linker workaround that we need to enable for the MT8173 SoC. When a certain pattern of instructions is placed at just the wrong offset, it may cause incorrect behavior and the linker must fix it up. One of the ways it may do that is adding an extra 4K of code.
The weird thing is that the added code isn't actually necessary for the way it is fixed up in our case. I think this is a binutils bug/limitation, I've filed https://sourceware.org/bugzilla/show_bug.cgi?id=24373 about it... but I wouldn't hold my breath about it being fixed anytime soon (it's a rare erratum for an old CPU revision, after all).
Anyway, for now either restricting this code to x86 or changing the MT8173 memlayout to make more space available sounds fine.