From mboxrd@z Thu Jan 1 00:00:00 1970 From: ben lamothe Subject: Re: Thinkpad T40 Fan Date: Thu, 5 Feb 2004 03:04:27 -0500 Sender: acpi-devel-admin-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Message-ID: <20040205030427.24025108.blamothe@mit.edu> References: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Errors-To: acpi-devel-admin-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , List-Archive: To: "Brown, Len" Cc: shaohua.li-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org, acpi-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: linux-acpi@vger.kernel.org Thanks for the reply. I tried to find a utility that monitored temperature in windows, but I was completely unsuccessful. Do you know of any? I was able to notice that after running windows for about three hours without the fan ever coming on, immediately after booting linux, the temperature was 107F, and the temperature is usually in the mid 80's from a cold boot. The fan came on after about 30 seconds, alot faster than normal (usually takes 10-15 minutes). I haven't noticed a consistent starting temperature for the fan, but generally it starts when it gets around 95F. I havn't noticed a stopping temperature either. As I said, I've noticed the fan running at temps as low as 80-85F. If I leave my room window open, then the fan shuts off after about 30 mins, but the THMO driver tells me that the temp is around 90F, which is really weird because I have definitely heard it loud and kicking at temps well below that. I vaguely remember the fan staying on after installing windows from scratch, but i am not completely sure as that was a long time ago and I didn't know about this fan problem, so I wasn't looking out for it. The vast majority of my other hardware didn't work either, I had to call and get restore cd's to get things working. I don't think that it's an I^2C device, because I think the documentation given to me by IBM would list such a thing, but I may be wrong. Out of your list of choices, it seems like #2 is most likely, because I can't imagine why a fan needs to run for a processor at a temp of 90F, so I don't think it's totally hardware. The fact that the fan is on so much may be a failsafe that IBM put in place just in case the OS doesn't know how to control the fan effectively, but that's just a guess. On Wed, 4 Feb 2004 21:44:14 -0500 "Brown, Len" wrote: > >> This behavior is not exibited in Windows, > >> on the contrary, the fan is almost never on. > > > ACPI can't control fan in many IBM systems, > > including T40. DSDT of T40 has no fan device defined. > > Hmm, how can Windows keep the fan off but Linux can't? > > As there is no ACPI fan device, there must be a different method to > control the fan on this box. > > 1. It may be some i2c device that Windows knows about but Linux does > not? > Maybe IBM ships some platform specific software with windows? > Would be interesting to know if a from-scratch install of the > generic non-IBM windows was still able to keep the fan off. > > 2. It may be some BIOS code using SMM that Linux somehow breaks? > > 3. It may be done entirely in hardware without the knowledge of the > OS? > > I'm hopeful that it is #3, and that Windows is simply doing better > passive cooling than Linux -- and perhaps we can perhaps improve our > passive cooling... > > Can you run some experiments? Maybe you can monitor the temperature > in windows to see if it really is cooler. Perhaps you can experiment > with the power management policy settings such that it is in > high-power mode instead of maximum battery mode and observe the > temperature rises, and at what temperature the fan starts running? > > Thanks, > -Len ------------------------------------------------------- The SF.Net email is sponsored by EclipseCon 2004 Premiere Conference on Open Tools Development and Integration See the breadth of Eclipse activity. February 3-5 in Anaheim, CA. http://www.eclipsecon.org/osdn