Re: [PATCH] xen/acpi-stub: Disable it b/c the acpi_processor_add is no longer called.

[Egger Christoph <chegger@amazon.de>]

I think, Xen can get C and P states from ACPI itself.
Why is Dom0 needed as a dependency at all?

Christoph

On 22.03.13 15:28, Konrad Rzeszutek Wilk wrote:
> With the Xen ACPI stub code (CONFIG_XEN_STUB=y) enabled, the power
> C and P states are no longer uploaded to the hypervisor.
>
> The reason is that the Xen CPU hotplug code: xen-acpi-cpuhotplug.c
> and the xen-acpi-stub.c register themselves as the "processor" type object.
>
> That means the generic processor (processor_driver.c) stops
> working and it does not call (acpi_processor_add) which populates the
>
>           per_cpu(processors, pr->id) = pr;
>
> structure. The 'pr' is gathered from the acpi_processor_get_info function
> which does the job of finding the C-states and figuring out PBLK address.
>
> The 'processors->pr' is then later used by xen-acpi-processor.c (the one that
> uploads C and P states to the hypervisor). Since it is NULL, we end
> skip the gathering of _PSD, _PSS, _PCT, etc and never upload the power
> management data.
>
> The end result is that enabling the CONFIG_XEN_STUB in the build means that
> xen-acpi-processor is not working anymore.
>
> This temporary patch fixes it by marking the XEN_STUB driver as
> BROKEN until this can be properly fixed.
>
> CC: jinsong.liu@intel.com
> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> ---
>   drivers/xen/Kconfig | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
> index 5a32232..67af155 100644
> --- a/drivers/xen/Kconfig
> +++ b/drivers/xen/Kconfig
> @@ -182,7 +182,7 @@ config XEN_PRIVCMD
>
>   config XEN_STUB
>   	bool "Xen stub drivers"
> -	depends on XEN && X86_64
> +	depends on XEN && X86_64 && BROKEN
>   	default n
>   	help
>   	  Allow kernel to install stub drivers, to reserve space for Xen drivers,
>