AMD low power hacks
Michael Nottebrock
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I've been wondering lately why my AthlonTB runs at a quite high
idle-temperature and I came across this page:
http://vcool.occludo.net/VC_Theory.html
Does someone feel like getting something similar into our kernel?
Regards,
--
Michael Nottebrock
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Terry Lambert
> I've been wondering lately why my AthlonTB runs at a quite high
> idle-temperature and I came across this page:
>
> http://vcool.occludo.net/VC_Theory.html
>
> Does someone feel like getting something similar into our kernel?
Note that this can not be made to be reliable without the
confidential errata for A4, A5, A6, A7, and A9. Otherwise,
you can/will get spurious system hangs.
I rather expect that this is the reason it's "off by default",
on most systems, and why there is a "BIOS override" that
disables it, on others.
-- Terry
Gary Jennejohn
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>
> idle-temperature and I came across this page:
>
> http://vcool.occludo.net/VC_Theory.html
>
> Does someone feel like getting something similar into our kernel?
>
If you have a VIA KT266A chipset then you can do something like this:
# turn on HALT bit in register 0x95 of the KT266a -> CPU runs much cooler
# NOTE: the register had 0x1c when I checked it
echo Enable halt bit in KT266A
/usr/sbin/pciconf -w -b pci0:0:0 0x95 0x1e
which I have in /etc/rc.local. My Athlon runs about 15 C cooler with
this. Bit 1 of register 0x95 controls idling of the CPU.
Here's a step-by-step description:
Do the following as root:
1) pciconf -l -v
this lists all the PCI chipsets found at boot time. I see
agp0@pci0:0:0: class=0x060000 card=0x30991106 chip=0x30991106 rev=0x00
hdr=0x00
vendor = 'VIA Technologies Inc'
device = 'VT8366/A Apollo KT266/A,KT333 CPU to PCI Bridge'
class = bridge
subclass = HOST-PCI
So I have a KT266(A) at pci0:0:0
2) pciconf -r -b pci0:0:0 0x95
0x1c
Bit 1 isn't set
3) pciconf -w -b pci0:0:0 0x95 0x1e
turns on bit 1.
---
Gary Jennejohn / ga...@jennejohn.org g...@freebsd.org g...@denx.de
Aaron Seelye
Aaron