linux-kernel - Re: [PATCH 1/4] genirq: Provide basic NMI management for interrupt lines

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Message-ID: <86r2jhw7a1.wl-marc.zyngier@arm.com>
Date:   Thu, 02 Aug 2018 08:35:02 +0100
From:   Marc Zyngier <marc.zyngier@....com>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>,
        Julien Thierry <julien.thierry@....com>,
        LKML <linux-kernel@...r.kernel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>
Subject: Re: [PATCH 1/4] genirq: Provide basic NMI management for interrupt lines

On Thu, 02 Aug 2018 07:55:49 +0100,
Thomas Gleixner <tglx@...utronix.de> wrote:
> 
> On Thu, 2 Aug 2018, Marc Zyngier wrote:
> > 
> > If we need to distinguish between the two, then we need two flags. One
> > that indicates the generation capability, and one that indicates the
> > forwarding capability.
> 
> There is absolutely no reason to expose this on x86, really.
> 
> Why?
> 
> Because NMI is an utter trainwreck on x86. It's a single entry point
> without the ability of differentiation from which source the NMI
> originated. So mapping it to anything generic is just not going to work.
> 
> It has absolutely nothing to do with the normal way of vector based
> interrupt operation and I don't see at all how adding this just because
> would improve anything on x86. In fact it would create more problems than
> it solves.

Fair enough. Does it mean Julien can completely ignore the x86
requirements for this and focus on something that fit the need of
architectures where (pseudo-)NMIs can be managed similarly to normal
interrupts (arm, arm64, sparc...)?

Thanks,

	M.

-- 
Jazz is not dead, it just smell funny.