19 Jun
2009
19 Jun
'09
7:59 p.m.
the way SMP works, the BSP sets up its ram. At that point, the APs can use the BSP ram. That's why APs have a stack in the first place.
APs have a working stack when they are setting up their own RAM.
The way this works on amd64 is that the AP comes up, goes to cache as ram, finds it is an AP and goes to sleep again. Then it wakes up again in stage2 when the BSP sends an IPI. At this point (at least remote) RAM is available. They never set up their own ram (in terms of Jedec init, or setting up a ram controller), but only have to clear it, in case of ECC memory.
OK. I'd thought that they each initialized their own RAM, then went to sleep. Thanks.
Myles