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Crispy Beef
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Joined: 29 Apr 2003
Posts: 194
Location: UK

PostPosted: Mon Sep 14, 2009 9:36 am    Post subject: PowerMac G5 Shutdown Problem Reply with quote

Hi,

I used to run a B&W G3 with Gentoo, but have recently switched to a G5. It's currently running Debian as I needed it up and running quickly, but in a lot of ways I miss Gentoo, plus there are a few issues with the Debian install. The main issues I have come across are documented here:

http://forums.debian.net/viewtopic.php?f=5&t=40719

Based on what I've mentioned in the thread above, has anybody experienced them with a gentoo install and the same - or similar - hardware? If the fans and everything work correctly I'll spend the time to switch back to Gentoo. :)
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bmaass
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Joined: 15 Mar 2008
Posts: 25

PostPosted: Thu Sep 17, 2009 12:22 pm    Post subject: Reply with quote

I have a Quad G5 here, which is the last model G5 ever produced. Everything is working splendid, thermal control of pumps/fans included.
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Crispy Beef
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Joined: 29 Apr 2003
Posts: 194
Location: UK

PostPosted: Thu Sep 17, 2009 12:31 pm    Post subject: Reply with quote

bmaass wrote:
I have a Quad G5 here, which is the last model G5 ever produced. Everything is working splendid, thermal control of pumps/fans included.


As far as I'm aware the newer PowerMacs make use of the windfarm kernel module for thermal control, my PowerMac is a 7,3, you can see what you have if you run the command:

Code:
$ cat /proc/cpuinfo
processor   : 0
cpu      : PPC970FX, altivec supported
clock      : 2000.000000MHz
revision   : 3.0 (pvr 003c 0300)

processor   : 1
cpu      : PPC970FX, altivec supported
clock      : 2000.000000MHz
revision   : 3.0 (pvr 003c 0300)

timebase   : 33333333
platform   : PowerMac
model      : PowerMac7,3
machine      : PowerMac7,3
motherboard   : PowerMac7,3 MacRISC4 Power Macintosh
detected as   : 336 (PowerMac G5)
pmac flags   : 00000000
L2 cache   : 512K unified
pmac-generation   : NewWorld


The kernel module for the older PowerMacs is therm_pm72 off of the top of my head.
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ssvb
Tux's lil' helper
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Joined: 06 Nov 2003
Posts: 96

PostPosted: Fri Nov 13, 2009 11:38 pm    Post subject: Reply with quote

Hi, I bought power mac g5 (2.3GHz dual processor, PowerMac7,3) just a few days ago and looks like I encountered exactly the same problem.

By looking in therm_pm72.c source file, seems like there is some kind of 'smart' logic which tries to calculate RPM for CPU fans based on the temperature and the current consumed. Additionally these is some backup emergency logic (in the case when the 'smart' part fails) which just simply blows up fans to the highest speed upon reaching some critical temperature, and exceeding this critical temperature by 8 degrees forces a shutdown.

In my case seems like the 'smart' logic is behaving very dumb and it just runs fans at inadequately low speed. That's why the temperature rises quite fast and the emergency logic periodically kicks in when CPU is doing some work (emerge -e world, or just some video playback).

I have patched this driver with a simple fix to add some extra code which introduces minimal speed limit depending on the temperature and testing it now. It should be completely safe because all what it does is just sometimes forcing the fans to run faster that they would be without this change. I wonder if it is a bug in the driver, or just some calibration data is messed up?
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Crispy Beef
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Joined: 29 Apr 2003
Posts: 194
Location: UK

PostPosted: Sat Nov 14, 2009 10:33 am    Post subject: Reply with quote

I've since seen a couple of patches for the kernel module that I guess do a similar thing and increase the base speed that the fans operate at. I haven't tried these as my solution for now has been to limit the CPU frequency to 2GHz, at this speed the fans keep both CPUs cool enough not to shutdown the system. While this is not a long term fix it has worked and allowed me to continuing working in the interim.

This bug report was an interesting read.

https://bugs.gentoo.org/100023
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