From: Russell King - ARM Linux <linux@arm•linux.org.uk>
To: "Rafael J. Wysocki" <rafael@kernel•org>
Cc: Marc Zyngier <marc.zyngier@arm•com>,
Peter Zijlstra <peterz@infradead•org>,
Viresh Kumar <viresh.kumar@linaro•org>,
"linux-pm@vger•kernel.org" <linux-pm@vger•kernel.org>,
"Rafael J. Wysocki" <rafael.j.wysocki@intel•com>,
Linux Kernel Mailing List <linux-kernel@vger•kernel.org>,
linux-next@vger•kernel.org,
"linux-arm-kernel@lists•infradead.org"
<linux-arm-kernel@lists•infradead.org>,
Guenter Roeck <linux@roeck-us•net>
Subject: Re: Crashes in arm qemu emulations due to 'cpufreq: governor: Replace timers with utilization ...'
Date: Mon, 15 Feb 2016 19:07:00 +0000 [thread overview]
Message-ID: <20160215190700.GN10826@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <CAJZ5v0gfOVyoWeee5jg7NxLFm-xwdA6-sPQV+cJ=NWJOV-wYzg@mail.gmail.com>
On Mon, Feb 15, 2016 at 07:54:26PM +0100, Rafael J. Wysocki wrote:
> On Mon, Feb 15, 2016 at 7:49 PM, Marc Zyngier <marc.zyngier@arm•com> wrote:
> > Given that OMAP3 is a UP system, there is zero chance that it has
> > registered the magic hook that delivers IPIs (its interrupt controller
> > is not even capable of doing so).
> >
> > I don't really know the context, but IPIs on a UP system seem at best odd.
>
> That would explain it, thanks.
>
> So it looks like we should always use irq_work_queue() on UP even if
> CONFIG_SMP is set, shouldn't we?
irq_work_queue_on() doesn't check whether 'cpu' is the CPU that we're
running on. This is a problem where we want to be able to run a kernel
built for SMP on a UP system.
I guess the question is whether irq_work_queue_on() is buggy, or whether
our implementation of arch_send_call_function_single_ipi() is buggy.
Should arch_send_call_function_single_ipi() do something on UP systems,
if so what?
We don't have IPIs on UP systems, so we can't raise any interrupts.
So, should we call generic_smp_call_function_interrupt() directly
from it?
Some clues would be good...
--
RMK's Patch system: http://www.arm.linux.org.uk/developer/patches/
FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
according to speedtest.net.
next prev parent reply other threads:[~2016-02-15 19:07 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-15 17:05 Crashes in arm qemu emulations due to 'cpufreq: governor: Replace timers with utilization ...' Guenter Roeck
2016-02-15 18:41 ` Rafael J. Wysocki
2016-02-15 18:49 ` Rafael J. Wysocki
2016-02-15 18:49 ` Marc Zyngier
2016-02-15 18:54 ` Rafael J. Wysocki
2016-02-15 19:03 ` Marc Zyngier
2016-02-15 19:12 ` Rafael J. Wysocki
2016-02-15 19:28 ` Rafael J. Wysocki
2016-02-15 19:42 ` Tony Lindgren
2016-02-15 19:46 ` Guenter Roeck
2016-02-15 19:57 ` Tony Lindgren
2016-02-15 19:23 ` Russell King - ARM Linux
2016-02-15 20:41 ` Rafael J. Wysocki
2016-02-15 19:07 ` Russell King - ARM Linux [this message]
2016-02-15 19:01 ` Tony Lindgren
2016-02-15 19:40 ` Guenter Roeck
2016-02-15 19:58 ` Tony Lindgren
2016-02-15 20:09 ` Guenter Roeck
2016-02-15 20:38 ` Rafael J. Wysocki
2016-02-15 20:37 ` Rafael J. Wysocki
2016-02-15 21:36 ` Tony Lindgren
2016-02-16 1:38 ` Guenter Roeck
2016-02-15 19:02 ` Russell King - ARM Linux
2016-02-16 1:13 ` Viresh Kumar
2016-02-16 1:27 ` Rafael J. Wysocki
2016-02-16 1:36 ` Viresh Kumar
2016-02-15 22:29 ` Peter Maydell
2016-02-15 23:19 ` Guenter Roeck
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