linux-kernel - Re: [PATCH v10 03/19] arm: fiq: Replace default FIQ handler

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Message-ID: <20140904094521.GB30401@n2100.arm.linux.org.uk>
Date:	Thu, 4 Sep 2014 10:45:21 +0100
From:	Russell King - ARM Linux <linux@....linux.org.uk>
To:	Daniel Thompson <daniel.thompson@...aro.org>
Cc:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	kgdb-bugreport@...ts.sourceforge.net, patches@...aro.org,
	linaro-kernel@...ts.linaro.org,
	John Stultz <john.stultz@...aro.org>,
	Anton Vorontsov <anton.vorontsov@...aro.org>,
	Colin Cross <ccross@...roid.com>, kernel-team@...roid.com,
	Rob Herring <robherring2@...il.com>,
	Linus Walleij <linus.walleij@...aro.org>,
	Ben Dooks <ben.dooks@...ethink.co.uk>,
	Catalin Marinas <catalin.marinas@....com>,
	Dave Martin <Dave.Martin@....com>,
	Fabio Estevam <festevam@...il.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Nicolas Pitre <nico@...aro.org>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH v10 03/19] arm: fiq: Replace default FIQ handler

On Thu, Sep 04, 2014 at 10:09:20AM +0100, Daniel Thompson wrote:
> On 03/09/14 20:34, Russell King - ARM Linux wrote:
> > I would say that the ARM specific changes to entry-armv.S and setup.c
> > are correct.  All that you're doing there is to replace the existing
> > default no-op FIQ handler with some additional code which gets us into
> > SVC mode and back out, but itself is also a no-op.  In other words, no
> > real change.
> > 
> > That's a good first patch, and one which I would actually like to have
> > in my tree sooner rather than later, so that I can split that out from
> > my prototype code.
> 
> So would I!
> 
> I did some rebasing yesterday to put anything to do with kgdb right at
> the back of the queue. This "good first patch" is now actually the first
> patch; where the nofifier used to be it currently calls do_unexp_fiq()
> making it very close to "no real change".
> 
> BTW do_unexp_fiq() calls printk() but

You're making the assumption that something called do_unexp_fiq() before
your patches.  It seems that that function is dead code, and now that
you've pointed that out, I will kill this function.

The current situation is that if the CPU receives a FIQ, it enters the
FIQ vector, which contains an immediate return instruction.

> If you want me to work with something more recent then feel free to
> point me at it...

I'll post some of that stuff later today, probably this evening.

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