FreeBSD9 running CPUs slow on PowerMac7,2

[Matthew Rezny]

Thank you very much Justin and Andreas! That would explains the problem, and I just tested to confirm the system boots full speed when not stopping at the OF prompt. Good to have this solved, though I hope to be able to better solve it.

When I was trying 8.x previous, the boot from CD with C worked. Once I had an installed system, I could choose that disk as the startup disk in OS X and reboot to FreeBSD temporarily. When I tried to boot the 9.0 CD, something was read from the disk but then then half the colors go inverse while it keeps flashing the missing boot folder icon. So, to get the CD booted I had to do so from the OF prompt. I had left it stopping at the prompt for now due to the difficulty in even getting to this point.

I don't have a Mac keyboard, nor do I have anything with a "Windows" key to plug into it, so armed with a stack of true 101 key keyboard, I can't invoke any boot time option that needs the cmd/apple key. This machine also has the issue that the boot selector accessed by holding alt/option simply does not work, never has since it was new. So, to get to an OF prompt, I had to boot a OS X install DVD, bring up Terminal and use nvram tool to set auto-boot?=false. I was reluctant to change that back since it took such effort to set it in the first place, but in retrospect I guess I could have saved many hours of trying other things had I even thought to change that. Is there any way to change OD variable from FreeBSD as can be done under OS X with nvram command? That would make it easier to get the prompt back when needed as long as the system is still booting.

Now I'm running at full speed, 2000.20Mhz according to dmesg. It also seems my guess at the source of the issue is probably right, the loader gets something screwed up before the kernel even starts and then the kernel is helpless to fix it. The loader behaves different depending how it's invoked, and that seems like a bug worth fixing. Unfortunately, I know little about the loader and feel unprepared to tackle it since I have only one machine such machine and thus no easy way to debug things running from OpenFirmware. I had already looked at the loader code with an eye to get ZFS booting and decided I'm not ready to tackle it yet.

Having proper support in cpufreq for the SMU-less G5s would be beneficial in that it would allow power control as well as give a way to resolve this for cases where booting from the OF prompt may be necessary. Also, I have enough experience on other platforms with GPIO and I2C to feel confident messing with such things on this machine. I noticed there is an assortment of GPIOs with no driver attached, and numerous I2C devices also without drivers attached. I already made a list of the chips on the I2C bus with the intent to look them up later. The individual GPIO looks uninteresting for this going by the names Apple uses. I think everything interesting is sitting on I2C. All the monitoring chips are now supported, DS1775 and MAX6690 for temperature, AD7417 for voltage and current. That leaves a few other chips to look at and the labels Apple seems to confirm their purpose. There are two called i2c-hwclock, cy2213 "High Frequency Programmable PECL Clock Generator" and cy28508  "Power PC System Clock", which I suspect are controlling both CPU and bus clocks. There is a pair of pca9556s labeled i2c-cpu-voltage, which are basically GPIO expanders and I suspect are controlling CPU voltage, one per chip. There are also a pair of serial EEPROMs, labeled cpuid, which I think are on each CPU board and just contain the parameters to identify the chip to the motherboard. There's one more device labeled 'cereal' but I couldn't find a part number for the chip. Is anyone working on these?

On 3 Oct, 2012, at 6:26, Andreas Tobler wrote:

> On 03.10.12 04:41, Justin Hibbits wrote:
>> On Wed, 3 Oct 2012 01:17:08 +0200
>> Matthew Rezny <mrezny at hexaneinc.com> wrote:
>> 
>>> Tue Oct 2 22:49:53 UTC 2012 Jason bacon wrote:
>>>> Did you try enabling powerd?  ( powerd_enable="YES" in rc.conf,
>>>> "man powerd" )
>>>> 
>>>> I had this issue with an iBook some time ago, and Nathan W. pointed
>>>> out that Macs boot at the lower CPU freq, so you have to change it
>>>> manually with sysctl or run powerd to control it automatically.
>>> 
>>> I do have that in rc.conf, but powerd has no way to control the
>>> clockrate without cpufreq available.
>>> 
>>> # powerd
>>> powerd: lookup freq: No such file or directory
>>> 
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>> 
>> Andreas Tobler posted something related to this a while back on the
>> list.  His suggestion at the time was to autoboot to FreeBSD, and not
>> boot via the Open Firmware prompt.  If you're already doing that, I'm
>> clueless.
>> 
>> The relevant link I found is
>> http://freebsd.1045724.n5.nabble.com/Fan-Power-controls-td4170991.html
> 
> Justin is right here. The only option you have is autoboot to get the full CPU frequency.
> These machines have a complicated way to setup the full CPU frequency and I do not know if it is worth hacking here when one can get the value with autobooting.
> 
> Here in the last section 'Booting into FreeBSD' you find how to do this.
> 
> http://people.freebsd.org/~nwhitehorn/ppcinstall.txt
> 
> Hope this helps.
> Andreas
>