Finally got it to work by trial and error. If I boot the machine with 'noapic' and remove all splash and vga= options I systematically get all cores recognized. Seems like 'noapic' is the real key here. Without it, booting can bring up 1, 2 or 4 cores in a seemingly random fashion.
Finally got it to work by trial and error. If I boot the machine with 'noapic' and remove all splash and vga= options I systematically get all cores recognized. Seems like 'noapic' is the real key here. Without it, booting can bring up 1, 2 or 4 cores in a seemingly random fashion.