[coreboot] locking...

Stefan Reinauer stepan at coresystems.de
Fri Jun 19 20:07:15 CEST 2009

Myles Watson wrote:
>>> So each AP has some part of RAM to copy the buffer to?
>> the way SMP works, the BSP sets up its ram. At that point, the APs can
>> use the BSP ram.
> For Opterons where each node has its own RAM this is a little bit more
> complex, right?
No, not really. This is already the complex case. Many systems only have
one memory controller. But on all coreboot systems, even those with
multiple memory controllers, the controllers are all set up by the BSP.
Parallelizing here makes only very little sense.

The reason we're parallelizing is you have to clear memory if you have
ECC on some (older?) systems where the memory controller is incapable of
doing that automatically. So when we have to clear 32G at a rate of 3 or
6GB/s we want to put that load on several CPUs, so it's 1-2s instead of
5-10. But the ram is all there at this point, and can be transparently
accessed by all CPUs.


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