From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 2 Dec 2014 00:55:36 +0100 From: Gilles Chanteperdrix Message-ID: <20141201235536.GK28038@hermes> References: <314E5ECDAA86314791309FA670550F89C9C4FD8A@SINTEFEXMBX05.sintef.no> <20141201151951.GG24110@csclub.uwaterloo.ca> <20141201153057.GJ23220@hermes> <20141201233554.GI24110@csclub.uwaterloo.ca> <20141201233720.GJ28038@hermes> <20141201235043.GJ24110@csclub.uwaterloo.ca> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20141201235043.GJ24110@csclub.uwaterloo.ca> Subject: Re: [Xenomai] WARNING: at arch/arm/kernel/ipipe.c:157 ipipe_set_irq_affinity+0x47/0x70() List-Id: Discussions about the Xenomai project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Lennart Sorensen Cc: "xenomai@xenomai.org" On Mon, Dec 01, 2014 at 06:50:43PM -0500, Lennart Sorensen wrote: > On Tue, Dec 02, 2014 at 12:37:20AM +0100, Gilles Chanteperdrix wrote: > > On Mon, Dec 01, 2014 at 06:35:54PM -0500, Lennart Sorensen wrote: > > > On Mon, Dec 01, 2014 at 04:30:57PM +0100, Gilles Chanteperdrix wrote: > > > > On the other hand, this is just a warning, it does not prevent the > > > > system from working, and this warning warns us about a real problem: > > > > we can not set the irq affinity of this driver. > > > > > > It was ugly and just a warning so I commented it out. > > > > > > I don't think the hardware has any way to do affinity, so it can't be > > > fixed, so the warning doesn't help. > > > > Yes, but now you know it, without the message, you would not know it. > > True, but it sure looks terrible in the logs given it looks about the > same as a kernel crash. To the uninformed yes. Kernel bugs begin with "BUG", kernel faults (which would be what is nearest from a kernel crash) begin with "Unhandled fault in kernel mode". Not with "Warning:". > > And I still don't think there is anything that can be done about it. > You can set the affinity of the GIC irq for the whole GPIO bank, but > not for the individual pins of the gpio bank. What I mean is that if you are writing a driver and you care about irq latency, this information is important, it tells you can not pin the irq handler to a particular core, and so that if you plan to have a good latency, you should probably find an irq source which is directly tied to the GIC, and avoid the GPIOs. -- Gilles.