Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1764291AbXJEUsL (ORCPT ); Fri, 5 Oct 2007 16:48:11 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1762541AbXJEUr6 (ORCPT ); Fri, 5 Oct 2007 16:47:58 -0400 Received: from hobbit.corpit.ru ([81.13.94.6]:22290 "EHLO hobbit.corpit.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752359AbXJEUr5 (ORCPT ); Fri, 5 Oct 2007 16:47:57 -0400 Message-ID: <4706A2F7.8050508@msgid.tls.msk.ru> Date: Sat, 06 Oct 2007 00:47:51 +0400 From: Michael Tokarev Organization: Telecom Service, JSC User-Agent: Icedove 1.5.0.12 (X11/20070607) MIME-Version: 1.0 To: Guennadi Liakhovetski CC: Greg KH , Alan Stern , Jean Delvare , linux-kernel@vger.kernel.org, i2c@lm-sensors.org, linux-usb-devel@lists.sourceforge.net Subject: Re: Various problems on Axis 700 Lite VIA C7 References: In-Reply-To: X-Enigmail-Version: 0.94.2.0 OpenPGP: id=4F9CF57E Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3772 Lines: 75 Guennadi Liakhovetski wrote: > Hi > > Ok, after a day of biseting, it turns out to be a compiler problem. The > gcc-3.3.5 produces at least these two problems (Oops on i2c-viapro probe > and disabled IRQs in USB), whereas 4.1.2 has no problem so far. Up to now > 3.3.5 had no problem compiling 2.6.20+ kernels here, for example, for P-II > SMP. Does it at all look realistic that such "random" run-time problems > are caused by a miscompilation?... I can't say about compilers (but it looks to me somewhat possible still), but I can say a bit about the platform/CPU. You can find my thread titled "VIA C7 anyone" from several months back in archives - that was my first expirience. Since that, I received several emails from others with similar problems. The things is that at least boards I'm using, but I suspect it's CPU not the board, -- are somewhat... flaky, so to say, and their reliability (or even ability to work) depends on several factors, starting with production conditions (environment at a time when it has been produced) and up to various thermal factors. It seems there's quite significant percentage of C7-based boards that are flaky/unreliable, replacing one with another from the same batch usually fixes the prob. Next, some boards are VERY sensitive to themperature, and their thermal sensors are WRONG - it seems - 100% of the time, showing ~20% less themperature than it really is (say, when the sensor shows 35 degrees celsius, the themp really is about 45..50 degrees) -- when the themperature (on SOME samples) grows above 40 degrees, the system becomes unreliable and may crash randomly here and there. More, due to geometry of the CPU chip, with very small square area that touches the headsink and relatively large headsink, it's sometimes enouth to just touch the headsink so it positions wrongly, with bad thermo-contact between the CPU and the headsink, resulting in high themperatures and system instability. And even more interesting -- it seems that some sequence of instructions are more frequently misinterpreted (under "abnormal" conditions above) than other sequences doing the same thing. That is, the same program compiled with gcc-3.4 may work almost 100% correct while the same thing compiled with gcc-4.1 may almost alway fail (usually due to segmentation fault), or exactly the opposite. So umm.... ;) I'm running VIA C7 on this machine where I'm typing right now - no single glitch since the time I replaced the failing one (at a time of mentioned thread), it's rock-solid. I even removed the fan from the headsink - the themp grows up to 70..80 degrees celsius (according to lm-sensors, so actual themperature should be higher) when I run CPU-intensive apps, and nothing breaks. Previous motherboard which I replaced (the same model, from the same batch) was breaking randomly, but worked relatively stable when placed on the street and with a large "external" fan used in rooms for ventilation... ;) even without any load when onboard sensors showed 35 degrees. That to say - it may be some miscompilations, but may be some probs with hardware itself. If you can, try to reproduce the same on another board (I just tried to boot 2.6.23-rc5 on this machine, compiled for PIII CPU using gcc-4.1.2 (no other version installed, sorry) - no issues so far). And no, I'm not trying to say "don't use ViA C7" etc -- I just love this my box, it's very good, powerful enouth and quiet. Just be prepared for some... issues, which happens - rarely but still. /mjt - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/