Re: [Xen-devel] Linux 3.4 dom0 kernel error loading xen-acpi-processor: Input/output error

[Pasi Kärkkäinen <pasik@xxxxxx>]

On Sat, Mar 09, 2013 at 12:18:20AM +0200, Pasi Kärkkäinen wrote:
> > > 
> > > I don't seem to have _PCT on my Ivy Bridge i7 laptop.. 
> > > 
> > > > In your case then .. lets go back to the start - the driver failed with 
> > > > -EIO
> > > > and it was v3.4.x kernel? Now that I've figured out the regression with 
> > > > v3.9
> > > > I can take a look at this.
> > > > 
> > > 
> > > Ok.
> > > 
> > > So the problem for me with Linux 3.4.32 kernel is "modprobe 
> > > xen-acpi-processor" fails:
> > > initcall xen_acpi_processor_init+0x0/0x6b0 [xen_acpi_processor] returned 
> > > with error code -5
> > > 
> > 
> > Great :-( On my box (SandyBridge i3 2100, MS-7680) it installs just fine. 
> > This is
> > v3.4.22 with 
> > 
> > cat linux-build/.config|grep PROCESSOR
> > CONFIG_ACPI_PROCESSOR=y
> > CONFIG_ACPI_PROCESSOR_AGGREGATOR=m
> > CONFIG_XEN_ACPI_PROCESSOR=m
> > 
> 
> I'm using:
> 
> CONFIG_ACPI_PROCESSOR=y
> CONFIG_ACPI_PROCESSOR_AGGREGATOR=m
> CONFIG_XEN_ACPI_PROCESSOR=m
> 

Do you see _PCT on your SandyBridge i3 DSDT? 

> 
> > 
> > > The error deeper down in the ACPI internals is:
> > > processor_perflib-0430 [00] processor_get_performa: ACPI-based processor 
> > > performance control unavailable
> > 
> > I think looking at the code, that even on baremetal you would not have
> > any P-states.
> > 
> > I am looking at the code, and the one thing that caught my eye is this 
> > comment:
> > 
> > /*
> >  * Do a quick check if the systems looks like it should use ACPI
> >  * cpufreq. We look at a _PCT method being available, but don't
> >  * do a whole lot of sanity checks.
> >  */
> > 
> > And since your machine has no _PCT, it just bypasses it.
> > 
> > Is there a BIOS option for power saving? Perhaps its off? 
> >
> 
> Hmm, good question, I'll have to check.. 
>

My Dell R510 BIOS has these settings:

Turbo Mode: Enabled.
C States: Enabled.
Power Management: "Active Power Controller".

Other options for "Power Management" include: "Custom", "OS Control" and 
"Maximum Performance".

I tried changing it to "OS Control", but then "modprobe xen-acpi-processor" 
gives error -19, "No such device".


> 
> > > 
> > > Function call path is this:
> > > 
> > > xen_acpi_processor_init()
> > >   acpi_processor_register_performance(perf, i)                    <-- 
> > > returns -EIO
> > >           acpi_processor_get_performance_info(pr)                 <-- 
> > > returns -ENODEV and prints the error to dmesg
> > >                   acpi_get_handle(pr->handle, "_PCT", &handle);   
> > >                           acpi_ns_get_node()                      <-- 
> > > doesn't find _PCT
> > > 
> > >   goto err_out;                                                   <-- 
> > > modprobe xen-acpi-processor fails
> > > 
> > > 
> > > The CPU in question is:
> > > Intel(R) Xeon(R) CPU L5640
> > > 
> > > ACPI DSDT.dsl is here:
> > > http://pasik.reaktio.net/dell-r510-acpi-dsdt.dsl
> > 
> > Oh wait, this is not an laptop! It is some rack-server.
> > 
> 
> Correct. It's a Dell R510 rack server.
> 

Did you mean that xen-acpi-processor driver is not needed on servers? 


-- Pasi


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