Previously on the resource allocator discussion, I was about to test Arthur's fix for PARALLEL_MP when all my boards suddenly failed to come up. I still refuse to let this legend die, so I managed to get it going again, and look what it did for me in return.
First, I plugged the flash chip with vendor firmware to rule out hardware failure. Came up just fine. Excellent! Swapped in my coreboot chip and tried to flash my copy of coreboot (which is still carrying PARALLEL_MP and the fix. It worked!). flashrom knows it has the 440BX chipset but can't seem to convince itself it will work. See the attached log. I have to calmly tell it "laptop=this is not a laptop" and then it works as usual. I don't remember ever having to do this before. Why? If I have a clue I can code up and submit a patch.
Back to how it failed to boot in the first place. The hard disk booting stalled after SeaBIOS. Took me hours but eventually I found a line in my serial log that there has been a DMA timeout. Turning UDMA off in devicetree.cb and flash again made it boot again. So I would have to revert 576315e1 (aka CB:40961), but I'm hesitant because that seemed like the reasonable thing to do and it should have worked. So I'm also unsure why it didn't.