From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtpauth.hypersurf.com (smtpauth.hypersurf.com [209.237.0.8]) by ozlabs.org (Postfix) with ESMTP id BE6B7DDED3 for ; Wed, 24 Dec 2008 07:55:08 +1100 (EST) Received: from [192.168.1.37] (66-81-71-92.bayarea.dialup.o1.com [66.81.71.92]) (authenticated bits=0) by smtpauth.hypersurf.com (8.14.2/8.14.2) with ESMTP id mBNKslgq009024 for ; Tue, 23 Dec 2008 12:55:01 -0800 (PST) Message-ID: <49514F57.2050705@hypersurf.com> Date: Tue, 23 Dec 2008 12:51:35 -0800 From: Kevin Diggs MIME-Version: 1.0 To: linuxppc-dev@ozlabs.org Subject: Re: schizophrenic G5 ... References: <494EDB3F.4090604@hypersurf.com> <20081223172245.792a9e2b@bopserverein.de> In-Reply-To: <20081223172245.792a9e2b@bopserverein.de> Content-Type: text/plain; charset=ISO-8859-1; format=flowed List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Christian Krafft wrote: > On Sun, 21 Dec 2008 16:11:43 -0800 > Kevin Diggs wrote: > > >>Hi, >> >> I have a water cooled dual 2.5 GHz G5 (Powermac7,3). It has >>YDL 6.0 on it. Using the stock YDL 2.6.23 kernel this machine >>"appears" to work fine. >> >> After finally getting it to boot under 2.6.27, it will shut >>itself off if put under any significant load. And it is doing it very >>quickly. Like within a few seconds of becoming busy. I just >>discovered it is spitting out messages about "temperature way above >>maximum" (from therm_pm72.c). >> > > > I have a very similar problem on my mac at work. > I don't know atm how to look up the critical temperature that is > fused. My mac reported only 55 degrees for the one cpu. > The critical temperature can be read from the device-tree if i remember > it correctly. > I heard that there exists a bootable CD which contains a tool to refuse > the CPU. Dont know where to download it, so my pragmatic solution was to > relocate the machine to a room with air conditioning ;-) > And I also run the ONE cpu at lowest frequency. > > ck > Critical temperature? If it is in the device tree are we sure it isn't (from the 970fx_thermal_diode_an, page 2, second paragraph): In the PowerPC970FX family, the thermal diode is calibrated at a specified calibration temperature, usually around 70C, with no power on the chip, VDD = 0.0V, and 100 micro-amps being driven through the diode. The voltage across the diode is measured; it should be between 0.60V and 0.80V. The measured voltage and temperature is stored in Thermal Diode Calibration fuse bits. A second lower temperature value is used to set the second calibration point, refer to the datasheet for this value. On page 3 it also has: Reading Thermal Diode Calibration Data Via JTAG In order to access the Thermal Diode Calibration data stored in each processor, a sequence of JTAG commands must be issued, usually over the IIC bus. By using JTAG commands, the desired data will appear serially on the PowerPC970FX TDO pin or can be read using IIC. The detailed information on how to perform the read operation of the calibration registers is found in the PowerPC970FX User s Manual. Reading the thermal diode calibration register should be a one-time-only procedure. It is assumed that the Thermal Diode Calibration data stored in each processor will be captured and stored in system ROM for subsequent use. kevin