RE: [Xen-ia64-devel] [PATCH] Add event callback for xen/ia64

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

>From: Tristan Gingold [mailto:Tristan.Gingold@xxxxxxxx]
>Sent: 2006年4月11日 20:30
>Le Mardi 11 Avril 2006 08:52, Tian, Kevin a écrit :
>> Add event callback for xen/ia64. Consequently the long
>> existing hardcode percpu evtchn_irq (0xe9) is abandoned
>> now.
>>
>> Currently only inter-domain event channels are injected
>> by this new path, like virtual drivers. Soon we'll bind
>> all physical irq/ipi/virq to this path to match our
>> agreement at last xen summit.
>Two questions:
>
>* why the register callback is not in the C code ?

Later in C code, currently in asm code, because callback
registration has to be issued much earlier like in start_kernel().
However currently those linux files are not modified, and thus
I just refine the modification in existing files like xensetup.S.
Later when xen/ia64 moves to real subarch like x86, then we
can change it to C code.

>
>* Performances ?

There should be no obvious difference. The importance here
is that this patch is only an intermediate step toward final
solution. It makes more sense to measure performance at the
last step when all pirq/virq/ipi are bound to this path. Finally it
should be better. Also please note this is necessary feature 
requirement to reuse common architecture and thus support 
more advanced features easily just like Isaku's p2m effort. The 
performance can be always tuned on top of this path gradually.

Thanks,
Kevin

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