[PATCH 1/4] powerpc/book3e: introduce external_input_edge exception handler for 64bit kernel

[Scott Wood]

On 05/11/2013 06:26:21 PM, Kevin Hao wrote:
> In the external proxy facility mode, the interrupt is automatically
> acknowledged with the same effect as reading the IACK register. So
> this makes external input interrupt more like edge sensitive. That
> means we can leave the irq hard enabled when it occurs with irq soft
> disabled just like the dec and doorbell interrupt. But the External
> Proxy Register(EPR) is only considered valid from the time that the
> external interrupt occurs until MSR[EE] is set to 1. So we have to
> save the EPR before irq hard enabled.

Is it really worth it?  Are you having a real-world problem with  
profilability as things stand, that this resolves?  We should already  
be no worse off than non-external-proxy hardware...

-Scott