Re: PowerMac G5 fans run out of control with kernel4.17.0-3-powerpc64 but not with 4.16.0-1-powerpc64
Hi Mark!
On Aug 25, 2018, at 8:52 PM, Mark G.B. <mark.balantzyan@gmail.com> wrote:
> Hello Rick and other PMac users,
>
> What kind of Powermac are you running the 4.17 kernel on? 11,2? 11,2 btw, I believe is the G5 Quad-core. Even with your reply, I may not come to a definitive conclusion. I will have to do some research, and I certainly am not nearly as well-versed as those on the Debian team.
>
> For reference, my own Powermac, an 7,2, does the EXACT same things, /etc/modules “windfarm_core” eliminates the tornado. How did you even find that fix? The origin of that fix may help us determine the backend-kernel functionality pointing porters in the right direction.
>
> Regards,
> Mark
To answer your questions:
It’s a G5 version “7,3”, with a 2.0 GHz dual-core/single-chip CPU, with 4GB RAM and a 120GB hard disk.
As I mentioned in my original email to this list,
> Back in the old days of Linux kernel 3.x, the fix for wind tunnel fans was to load the “i2c_powermac" kernel module. Nowadays, that module is built-in so it isn’t necessary (or even possible) to manually load it. I checked the config files, and it is still built-in on both the 4.16 and the 4.17 kernels.
The pre 4.x kernel “i2c_powermac” fix came from an old email on this list — I don’t remember who it was from. It seemed to be common knowledge on the list at the time — common enough that making the module built-in with the 4.x powerpc64 kernels was uncontroversial.
Then Dennis Clarke replied to my original email, mentioning that it might have something to do with “windfarm”. I had noticed that keyword in the list of available modules, so looking at the output of “lsmod” was an obvious first-step. When I noticed that “windfarm_core” (and a bunch of other “windfarm” modules that it depends on) were missing from the running 4.17 kernel, it seemed that doing “modload windfarm_core” was at least worth a try. I did try it, and it worked — the fans quieted down immediately. I put that knowledge together with the old information about “i2c_powermac” and gave it a try.
So the question we need to answer is: What happened between 4.16.0-1-powerpc64 and 4.17.0-3-powerpc64 kernels that automatically loaded the “windfarm_core” module in 4.16 but not in 4.17? And is the change a bug or a feature?
Enjoy!
Rick
> rbthomas@kmac:~$ 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
>
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