On Fri, Jun 19, 2009 at 9:02 AM, Carl-Daniel Hailfingerc-d.hailfinger.devel.2006@gmx.net wrote:
However, this locking has to work when some CPUs are in CAR and others are in RAM. And that's the big problem.
Let's go back to this original statement. I think it's not correct. We had decided, on opteron, that bsp does all memory setup -- i.e. sets up all memory controllers on all sockets. IIRC the opteron code starts APs up when all of memory is functional. I believe our Intel startup does this too: BSP sets up memory, and when APs start, memory is working and usable for stack etc.
If what I am saying is true, that all APs run AFTER the BSP has set up memory, then there is no issue: all locking can be based in memory, since NO AP needs to run in CAR mode -- memory is working. IIRC this is how K8 actually works.
So can we confirm my idea, that no AP need ever run in CAR? If they do need to run in CAR, why?
thanks
ron