[XenPPC] Re: if you easily see where I screwed up

[Jimi Xenidis <jimix@xxxxxxxxxxxxxx>]

moving to the list:
On Jun 20, 2006, at 11:39 PM, Orran Y Krieger wrote:
>  Jimi, would be good to sit with you one of those times so you can  
> point me to the first bits of code where I should be looking, and  
> remind me of what I am trying to do.
In case there is no sitting time and for the benefit of the list...
*** Note: expectations below are criticisms of your time not your  
talent. :-) ***
*** Warning! Manager Coding.. 'nuf said :-D ***

In xen/arch/ppc/boot_of.c you will find:
    cpu = of_getpeer(cpu);
    while (cpu > 0) {
        of_start_cpu(cpu, (ulong)spin_start, 0);
        cpu = of_getpeer(cpu);
    }

of_start_cpu() takes a devtree cpu node and asks OF to start it  
executing at the address spin_start, passing the third argument as  
spin_start's first (in r3).
*** NOTE: we don't bother to build a function descriptor for spin_start.

you will find spin_start at the bottom of arch/ppc/ppc64/exceptions.S

The first step would be to enumerate all the CPUs by giving each one  
a unique number (in r3) and having it set a bit in a shared ulong  
then spin on a barrier.  When all expected bits are set the booting  
cpu continues.
If you are gonna wait, then you can sample time base (mftb() and  
timebase_freq is one second) to know how much time goes by, if you  
don't get all acks within 2-3 seconds you have a bug.
--- I expect you to get this far, and you can have your yellow belt  
back ---
Later, after you have an allocator and are about to run the  
"idle_domain" you should release each CPU, (making sure they all have  
their own allocated stacks before they go C) and have them all  
rendezvous in the idle_domain.
--- I would like you to get this far, here you can have your blue  
belt back ---
After that, watch the world crumble and piece it back together.

--- I don't think I could stop you if I wanted to ---

-JX

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