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Re: [Xen-devel] [PATCH] x86/xsave: initialization improvements

>>> On 29.08.13 at 12:17, Andrew Cooper <andrew.cooper3@xxxxxxxxxx> wrote:
> On 29/08/13 10:39, Jan Beulich wrote:
>> - properly validate available feature set on APs
>> - also validate xsaveopt availability on APs
>> - properly indicate whether the initialization is on the BSP (we
>>   shouldn't be using "cpu == 0" checks for this)
>> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> Why is "cpu == 0" insufficient?
> The pcpu with id 0 is necessarily the BSP because of set_processor_id(0)
> early in __start_xen().

But eventually we will want/need to be able to hot-remove
CPU 0, and then some other CPU may later come back up
getting set its ID to zero. That shouldn't trigger one-time init
code paths.

I know this is not the only place, but as I come across them and
touch respective code anyway, I'm trying to fix those instances.


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