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SubjectRe: [PATCH HACK] powerpc: quick hack to get a functional eHEA with hardirq preemption
On Mon, Sep 15, 2008 at 03:13:32PM +0200, Sebastien Dugue wrote:
> > we are a bit worried about putting this into the mainstream part of non real
> > time linux.
> Heck, I sure do not want this to be applied mainstream nor into any tree.
> The sole purpose of this patch was to trigger some reaction from the people who
> know the hardware and try to understand where the problem lies.
> > There interrupts work perfectly fine, and it was a bit of a
> > challenge to get there for all cases / configurations / machines.
> Agreed, but the fact that it fails with hardirq preemption leads me to
> believe (without any more knowledge about the harware) that there might be
> something amiss with this driver (or the code concerning the XICS)
> nevertheless.
> >
> > Could you try to enable these changes only for RT-Linux via a real-time
> > kconfig switch?
> Nope, this is just a quick hack that allows me to have a functional eHEA under
> the rt kernel. I want to understand what the problem is:
> - Is the eHEA really delivering level interrupts to the XICS?
> - Is the XICS loosing interrupts when they are masked?

There is a known bug in the -rt kernels, the bug causes handlers
to lose edge interrupts.

See this patch:

> - ...?

Anton Vorontsov

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