Re: 2.6.27 kernel disables frequency switching on x86_64 - stuck on lowest frequency

Re: 2.6.27 kernel disables frequency switching on x86_64 - stuck on lowest frequency

[Linus Torvalds]

On Fri, 26 Sep 2008, Jason Vas Dias wrote:
> 
> There appears to be a serious problem with every 2.6.27-X kernel I've 
> tried - and I've tried quite a few from the linux-2.6, linux-acpi-2.6, 
> and linux-2.6-tip GIT trees, and the latest Fedora 10 kernels over the 
> past few weeks trying to solve this problem:

So which trees work, and which don't? Also, since it seems entirely 
repeatable, this is a prime candidate for "git bisect" - it will be 
eventually faster to do than trying many different trees at random, even 
if you will likely need to reboot/compile about 12 times or so (assuming 
2.6.27-rc1 is broken, and 2.6.26 works, which it sounds like).

Bisecting really isn't that hard. Get the git tree, do

	git bisect start
	git bisect bad v2.6.27-rc1
	git bisect good v2.6.26

and off you go. You don't even need to know a lot about git, there's a few 
quick tutorials out there if you haven't used it. See for example

	http://www.kernel.org/doc/local/git-quick.html

which has an example git bisect run, in addition to just initial clone 
insutrctions.

> CPU frequency switching is completely disabled, the 2.2Ghz AMD TL-64 
> Dual Core CPU is stuck at 0.8Ghz, the machine cannot reboot or perform 
> any ACPI actions.
> 
> There are no obvious failures indicated in the logs, only this:
> 
> [    0.000000] ACPI Error (tbfadt-0453): 32/64X address mismatch in "Pm2ControlBlock": [00008800] [0000000000008100], using 64X [20080609]

Hmm. I don't know if it's ACPI-related, but the fact that it cannot even 
reboot etc sure seems to make it likely. Have you made the acpi lists 
aware of it (linux-acpi@vger.kernel.org and lenb are listed in 
MAINTAINERS)?

		Linus

Re: 2.6.27 kernel disables frequency switching on x86_64 - stuck on lowest frequency

[Zhao Yakui]

On Fri, 2008-09-26 at 08:17 -0700, Linus Torvalds wrote:
> 
> On Fri, 26 Sep 2008, Jason Vas Dias wrote:
> > 
Hi, Jason
   Will you please attach the output of acpidump, dmesg?
   From the log it seems that the BIOS gives the incorrect ACPI table.
For example: the 32X/64X address don't match in FADT table.
   Of course you can open a new bug and attach the output of acpidump,
dmesg.
    http://bugzilla.kernel.org/acpi

thanks
     
> > There appears to be a serious problem with every 2.6.27-X kernel I've 
> > tried - and I've tried quite a few from the linux-2.6, linux-acpi-2.6, 
> > and linux-2.6-tip GIT trees, and the latest Fedora 10 kernels over the 
> > past few weeks trying to solve this problem:
> 
> So which trees work, and which don't? Also, since it seems entirely 
> repeatable, this is a prime candidate for "git bisect" - it will be 
> eventually faster to do than trying many different trees at random, even 
> if you will likely need to reboot/compile about 12 times or so (assuming 
> 2.6.27-rc1 is broken, and 2.6.26 works, which it sounds like).
> 
> Bisecting really isn't that hard. Get the git tree, do
> 
> 	git bisect start
> 	git bisect bad v2.6.27-rc1
> 	git bisect good v2.6.26
> 
> and off you go. You don't even need to know a lot about git, there's a few 
> quick tutorials out there if you haven't used it. See for example
> 
> 	http://www.kernel.org/doc/local/git-quick.html
> 
> which has an example git bisect run, in addition to just initial clone 
> insutrctions.
> 
> > CPU frequency switching is completely disabled, the 2.2Ghz AMD TL-64 
> > Dual Core CPU is stuck at 0.8Ghz, the machine cannot reboot or perform 
> > any ACPI actions.
> > 
> > There are no obvious failures indicated in the logs, only this:
> > 
> > [    0.000000] ACPI Error (tbfadt-0453): 32/64X address mismatch in "Pm2ControlBlock": [00008800] [0000000000008100], using 64X [20080609]
> 
> Hmm. I don't know if it's ACPI-related, but the fact that it cannot even 
> reboot etc sure seems to make it likely. Have you made the acpi lists 
> aware of it (linux-acpi@vger.kernel.org and lenb are listed in 
> MAINTAINERS)?
> 
> 		Linus
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