Re: [Xen-devel] çå: [PATCH]xen new latest version mp_register_lapic can't register disabled CPU, patch attempt to fix

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 07.07.15 at 12:23, <fanhenglong@xxxxxxxxxx> wrote:

Please don't top post.

> I payed attention to the appearance, beause my host start and trigger the 
> following code and printk logs
> printk("%sAPIC ID %#x and/or ACPI ID %#x beyond limit"
>                      " - processor ignored\n",
>                      processor->lapic_flags & ACPI_MADT_ENABLED ?
>                               KERN_WARNING "WARNING: " : KERN_INFO,
>                      processor->local_apic_id, processor->uid);
> 
> 
> after refered to the below comment in function acpi_parse_x2apic of xen 
> latest version 
> /*
>        * We need to register disabled CPU as well to permit
>        * counting disabled CPUs. This allows us to size
>        * cpus_possible_map more accurately, to permit
>        * to not preallocating memory for all NR_CPUS
>        * when we use CPU hotplug.
>        */
>       mp_register_lapic(processor->local_apic_id, enabled, 0);
> 
> 
> and compared with linux4.1 function acpi_parse_x2apic,
> this patch will be useful if xen host support CPU hotplug in the future,

But then mp_register_lapic() shouldn't be called with an out-of-
range LAPIC ID. I.e. I think if you wanted to address this
concern of yours, a more extensive change would be needed.

Jan


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