Re: mutex vs. local irqs (Was: 2.6.18 -mm merge plans)

[Roman Zippel]

Hi,

On Thu, 8 Jun 2006, Benjamin Herrenschmidt wrote:

> > On ppc it should not be that difficult to even modify the exception entry 
> > code. Instead of calling do_IRQ use do_early_IRQ and only install the real 
> > handler later.
> 
> Yes, it's possible, but will add overhead to the common  IRQ path just
> to handle an early boot special case.

What I mean is to directly patch the exception entry code, so after the 
initialization is complete you'll have no additional overhead.
In the EXC_XFER_TEMPLATE() macro the handler is stored at i##n. You can 
either export that address or you can use a special transfer handler, 
which automatically patches the values once some flag is set.

bye, Roman
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