Re: pv_ops smp support

[Jeremy Fitzhardinge <jeremy@goop.org>]

Zachary Amsden wrote:
> 1) What do you plan to do to address per-cpu data structures?

Er, what's there at the moment, more or less.  The main thing is that 
the secondary CPU get the PDA set up (init gdt and %gs) before anyone 
wants to use it (which is generally the first use of smp_processor_id() 
or current). At some point we'll probably fold the PDA and PER_CPU 
together.  Xen can more or less completely initialize the VCPU state 
before it is brought up, so there's little or no need for any kind of 
bootstrap code.

> 2) What is your remote TLB shootdown model?

Xen has a hypercall to shoot down a set of CPU's TLBs, so it doesn't 
need to do an IPI (we'll need to extend the flush_tlb interface to make 
good use of this).  It will still need IPIs for reschedule and remote 
function calls or course.

> Both of these could have major impacts on how you want to carve up 
> smp.c and smpboot.c.