Xen devel - May 2006 - RE: [Xen-ia64-devel] Re: PATCH: split smpboot.c and createcpuhotplug.c

>From: Tristan Gingold
>Sent: 2006年5月23日 15:30
>
>Le Lundi 22 Mai 2006 17:44, Keir Fraser a écrit :
>> On 22 May 2006, at 08:57, Tristan Gingold wrote:
>> > this patch creates a new file: cpuhotplug.c.  The content is the
>xenbus
>> > handler part of smpboot.c.  The purpose is to be able to share
this
>> > part with
>> > other architectures.
>> >
>> > Tested by compiling on i386.
>>
>> This raises the obvious question: why don''t you use the rest
of our
>> smpboot.c to implement SMP bringup? It''s all generic except
the bit
>> that sets up VCPU initial context.
>I can see three reasons:
>
>* Only a 10 lines change (IPI handling) was required in the linux kernel to
>run SMP on Xen.  All the other changes were in Xen.
>
>* xen/core/smpboot.c is not a drop in replacement for
>arch/ia64/kernel/smpboot.c  Surgery will be required.
>
>* If we used xen/core/smpboot.c, we''d lose transparent
virtualization.
>To
>re-enable it we had to do surgery again.
>
>Tristan.
Can''t is_running_on_xen help you with transparent virtualization?
Checks
on several major entry paths should be enough... 

The 2nd point seems more reasonable to me if logic does differ a lot.

Thanks,
Kevin

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