next/mmotm unbootable on G5: irqdomain

[Hugh Dickins]

On Mon, 23 Jul 2012, Benjamin Herrenschmidt wrote:
> On Sat, 2012-07-21 at 19:47 -0700, Hugh Dickins wrote:
> > I have to revert the patch below from mmotm 2012-07-20-16-30 or
> > next-20120720 in order to boot on the PowerPC G5: otherwise it
> > freezes before switching to the framebuffer console - but I'm
> > not certain where because that initial console doesn't scroll
> > (there are mpic messages at bottom and at top of screen, probably
> > later messages at the top but I don't know the sequence).
> 
> This fixes it

Confirmed: many thanks, Ben.

> (Grant, how do we avoid bisection breakage here ? I can
> put that in -powerpc and we can make sure that gets merged before your
> tree ?)
> 
> powerpc/mpic: Create a revmap with enough entries for IPIs and timers
> 
> The current mpic code creates a linear revmap just big enough for all
> the sources, which happens to miss the IPIs and timers on some machines.
> 
> This will in turn break when the irqdomain code loses the fallback of
> doing a linear search when the revmap fails (and really slows down IPIs
> otherwise).
> 
> This happens for example on the U4 based Apple machines such as the
> dual core PowerMac G5s.
> 
> Signed-off-by: Benjamin Herrenschmidt <benh at kernel.crashing.org>
> ---
> diff --git a/arch/powerpc/sysdev/mpic.c b/arch/powerpc/sysdev/mpic.c
> index 906f29c..bfc6211 100644
> --- a/arch/powerpc/sysdev/mpic.c
> +++ b/arch/powerpc/sysdev/mpic.c
> @@ -1376,7 +1376,7 @@ struct mpic * __init mpic_alloc(struct device_node *node,
>  	mpic->isu_mask = (1 << mpic->isu_shift) - 1;
>  
>  	mpic->irqhost = irq_domain_add_linear(mpic->node,
> -				       last_irq + 1,
> +				       intvec_top,
>  				       &mpic_host_ops, mpic);
>  
>  	/*
> 
> 
>