Re: [Xen-devel] [PATCH] initialize some more cpuinfo fields

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 8 May 2006, at 15:52, Jan Beulich wrote:

> > set up the cpu_to_apicid array at the same time. Why not lie about
> > cpu_data->apicid, and set phys_proc_id[cpu], at the same time in the
> > same function?
> Certainly an option, but keeping it in cpu_bringup() will allow easier 
> change once the dom0 special casing you talked
> about would be wanted/needed (because then you clearly *want* to call 
> identify_cpu() and not lie about anything).
How early during boot do these things need to be set up? We may also 
want to support static NUMA topologies for domU guests as well, under 
some circumstances. Is it okay to set that up in cpu_bringup() even 
though the CPUs may be brought online only after the OS is fully 
booted? Or is it better to set up the mapping arrays and so on early in 
smp_prepare_cpus()? The latter is possible since vcpu0 could 
interrogate Xen via a new vcpu_op sub-hypercall.
I think I'd rather keep the code where it is for now, and simply add 
identify_cpu() to cpu_bringup() later when we support that for domain0. 
That will simply act as a dynamic reconfiguration of the mappings and 
relationships that get simply statically initialised in 
smp_prepare_cpus().
 -- Keir


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