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

[Fanhenglong <fanhenglong@xxxxxxxxxx>]

-----邮件原件-----
发件人: Jan Beulich [mailto:JBeulich@xxxxxxxx] 
发送时间: 2015年7月7日 18:54
收件人: Fanhenglong
抄送: Hanweidong (Randy); Huangpeng (Peter); Yanqiangjun; xen-devel@xxxxxxxxxxxxx
主题: Re: 答复: [Xen-devel] [PATCH]xen new latest version mp_register_lapic can't 
register disabled CPU, patch attempt to fix

>>> 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.


Now, xen host can not support cpu hotplug,
I also think it is only not essential optimization,



Thanks
Henglong Fan










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