linux-kernel - Fate of CONFIG_IRQ

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Message-ID: <87zf7vex6h.wl-maz@kernel.org>
Date: Sat, 06 Dec 2025 10:12:22 +0000
From: Marc Zyngier <maz@...nel.org>
To: Daniel Lezcano <daniel.lezcano@...aro.org>,
    Thomas Gleixner <tglx@...utronix.de>
Cc: Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Fate of CONFIG_IRQ_TIMINGS and co

Hi both,

While fixing some ancient MIPS crap, I noticed that the IRQF_TIMER
flag wasn't being provided to any clockevent driver that uses percpu
interrupts, starting with the ARM architected timer.

Thinking that I might as well be fixing that, I started to dig into
it, only to realise that it is simply impossible to enable the IRQ
timing subsystem (CONFIG_IRQ_TIMINGS isn't selectable by a luser, and
TEST_IRQ_TIMINGS depends on it...).

Even if I manually hack the Kconfig to compile the timing
infrastructure and allow the selftest to be selected, nothing really
makes use of this, as the static key that controls the accounting is
never flipped. The selftest itself only cares about the accounting
data structure, and not interrupts.

This appears to be dead code, and seems to have been so for the past 6
years.

The obvious question is therefore: why do we have it the first place?
It isn't finished, not plugged in, and if it was, would fail to
correctly account for exactly 100% of the timer interrupts on the
systems I care about.

If this is a work in progress and that there is a line of sight to
having it working upstream, that's great, and I will happily post the
few fixes I have for it. Otherwise, can we do ourselves a favour and
consider dropping it?

Thanks,

	M.

-- 
Jazz isn't dead. It just smells funny.