On Sat, Jul 15, 2017 at 12:53 AM, Benjamin Herrenschmidt email@example.com wrote:
On Fri, 2017-07-14 at 13:46 +0200, Linus Walleij wrote:
I have this pretty nasty problem when trying to boot up a fresh openSuSE DVD on a PowerMac G5: the kernel by default does not have CONFIG_WINDFARM_PM72 enabled, with the effect that the cooling is not functioning.
The BIOS on the PowerMac G5 reacts to this by, after a grace period when the BIOS has waited for the OS to take over, increasing the fan speeds so it sounds like an airplane is in the room, and after another grace period simply cutting the power to the machine. This is done not beacuse the cooling is not working, but because the BIOS is not recieving handover of cooling from the OS, so it panics and give up. The problem has been reported by Linux users online.
It's not actually the BIOS but the fan controller HW who does that.
OK then :)
Are you running this hardware BTW?
I think this will make install images work in the G5 Macs.
Why is it not the job of the defconfig ? I was under the impression that just "selecting" like this was frowned upon ? I don't care much either way mind you, I'll let Michael decide what he wants to do.
I think nobody is happy with Kconfig really.
This relates to a recent Kconfig unmanageability discussion at ksummit-discuss I'd say. The situation is not great, it is very hard to make working configs and this patch is meant to help with that using the crude tools we have.
I prefer to just think about making it easy to do the right thing. And making Kconfig do the right thing without human intervention, because humans just screw everything up. As is proven by the openSuSE install media situation.
They simply have no clue what to enable to create an installable powermac media, even though they obviously know their way around ppc64, it's just too hard to get the Kconfig right.
So if I patch arch/arm/configs/g5_defconfig it starts working for me, true.
But I would not be surprised if the distros just forget to sync their configs with g5_defconfig so it doesn't help at all but instead I have to go and poke everyone and their dog about it.
Debian obviously had this enabled in *their* defconfig, because that installed just fine with their Jessue distro. They have since dropped support for ppc64 yay.
An alternative option is to go in and patch drivers/cpufreq/Kconfig.powerpc like that:
config CPU_FREQ_PMAC64 bool "Support for some Apple G5s" depends on PPC_PMAC && PPC64 + select WINDFARM + select WINDFARM_PM81 + select WINDFARM_PM72 + select WINDFARM_RM31 + select WINDFARM_PM91 + select WINDFARM_PM112 + select WINDFARM_PM121
If that is preferred?
Yours, Linus Walleij