DragonFly kernel List (threaded) for 2007-10
Re: pmap of amd64
I should add a clarification regarding the per-cpu info. I think the
distinction should be as a separate PML4 entry and not a PDP entry. This
way the kernel can have a single PDP/PD hierarchy that is shared across
The per-cpu magic can be statically hardwired for each cpu via a PML4
entry and maybe a few other pages (per-cpu) creating a PDP/PD
hierarchy. There are two ways to do it.
(1) We can map a page containing the address of the per-cpu globaldata
structure and use %fs in the trap code:
(2) We can map the actual per-cpu globaldata to a fixed address and access
Either way will work. I will note that the system code expects 'mycpu'
to be a variable kernel space address representing the location of the
globaldata structure in kernel space and it will get confusde if
'mycpu' returns the same fixed address on every cpu. So the %fs method
may be the best way to go so we don't have to run through all the system
code changing the expectations for 'mycpu'.