Re: get_irq_regs() from soft IRQ

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On Mon, Jun 29, 2009 at 05:35:37PM +0200, Jean Pihet wrote:
> On Monday 29 June 2009 17:19:31 Russell King - ARM Linux wrote:
> > It's one of these things that nests itself - when you have several IRQs
> > being processed on one CPU, there are several register contexts saved,
> > and get_irq_regs() returns the most recent one.
> >
> > > The use case is that the performance unit (PMNC) of the Cortex A8 has
> > > some serious bug, in short the performance counters overflow IRQ is to be
> > > avoided.
> >
> > I don't follow.  None of the PMNC support code in the mainline kernel
> > uses get_irq_regs() outside of IRQ context.
>
> That is correct. The Cortex A8 needs some special treatment.
> The errata says that if the counters are overflowing at the same time as a 
> coprocessor access is performed, the perf unit gets reset and/or locks up. In 
> short the counters overflow is to be avoided and so the PMNC IRQ.

Are you talking about 628216?
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