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This driver solves three problems:
1). Parse and upload ACPI0007 (or PROCESSOR_TYPE) information to the
hypervisor - aka P-states (cpufreq data).
2). Upload the the Cx state information (cpuidle data).
3). Inhibit CPU frequency scaling drivers from loading.
The reason for wanting to solve 1) and 2) is such that the Xen hypervisor
is the only one that knows the CPU usage of different guests and can
make the proper decision of when to put CPUs and packages in proper states.
Unfortunately the hypervisor has no support to parse ACPI DSDT tables, hence it
needs help from the initial domain to provide this information. The reason
for 3) is that we do not want the initial domain to change P-states while the
hypervisor is doing it as well - it causes rather some funny cases of P-states
transitions.
For this to work, the driver parses the Power Management data and uploads said
information to the Xen hypervisor. It also calls acpi_processor_notify_smm()
to inhibit the other CPU frequency scaling drivers from being loaded.
Everything revolves around the 'struct acpi_processor' structure which
gets updated during the bootup cycle in different stages. At the startup, when
the ACPI parser starts, the C-state information is processed (processor_idle)
and saved in said structure as 'power' element. Later on, the CPU frequency
scaling driver (powernow-k8 or acpi_cpufreq), would call the the
acpi_processor_* (processor_perflib functions) to parse P-states information
and populate in the said structure the 'performance' element.
Since we do not want the CPU frequency scaling drivers from loading
we have to call the acpi_processor_* functions to parse the P-states and
call "acpi_processor_notify_smm" to stop them from loading.
There is also one oddity in this driver which is that under Xen, the
physical online CPU count can be different from the virtual online CPU count.
Meaning that the macros 'for_[online|possible]_cpu' would process only
up to virtual online CPU count. We on the other hand want to process
the full amount of physical CPUs. For that, the driver checks if the ACPI IDs
count is different from the APIC ID count - which can happen if the user
choose to use dom0_max_vcpu argument. In such a case a backup of the PM
structure is used and uploaded to the hypervisor.
[v1-v2: Initial RFC implementations that were posted]
[v3: Changed the name to passthru suggested by Pasi Kärkkäinen <pasik@iki.fi>]
[v4: Added vCPU != pCPU support - aka dom0_max_vcpus support]
[v5: Cleaned up the driver, fix bug under Athlon XP]
[v6: Changed the driver to a CPU frequency governor]
[v7: Jan Beulich <jbeulich@suse.com> suggestion to make it a cpufreq scaling driver
made me rework it as driver that inhibits cpufreq scaling driver]
[v8: Per Jan's review comments, fixed up the driver]
[v9: Allow to continue even if acpi_processor_preregister_perf.. fails]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
199 lines
6.9 KiB
Plaintext
199 lines
6.9 KiB
Plaintext
menu "Xen driver support"
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depends on XEN
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config XEN_BALLOON
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bool "Xen memory balloon driver"
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default y
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help
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The balloon driver allows the Xen domain to request more memory from
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the system to expand the domain's memory allocation, or alternatively
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return unneeded memory to the system.
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config XEN_SELFBALLOONING
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bool "Dynamically self-balloon kernel memory to target"
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depends on XEN && XEN_BALLOON && CLEANCACHE && SWAP && XEN_TMEM
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default n
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help
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Self-ballooning dynamically balloons available kernel memory driven
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by the current usage of anonymous memory ("committed AS") and
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controlled by various sysfs-settable parameters. Configuring
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FRONTSWAP is highly recommended; if it is not configured, self-
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ballooning is disabled by default but can be enabled with the
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'selfballooning' kernel boot parameter. If FRONTSWAP is configured,
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frontswap-selfshrinking is enabled by default but can be disabled
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with the 'noselfshrink' kernel boot parameter; and self-ballooning
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is enabled by default but can be disabled with the 'noselfballooning'
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kernel boot parameter. Note that systems without a sufficiently
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large swap device should not enable self-ballooning.
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config XEN_BALLOON_MEMORY_HOTPLUG
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bool "Memory hotplug support for Xen balloon driver"
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default n
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depends on XEN_BALLOON && MEMORY_HOTPLUG
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help
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Memory hotplug support for Xen balloon driver allows expanding memory
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available for the system above limit declared at system startup.
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It is very useful on critical systems which require long
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run without rebooting.
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Memory could be hotplugged in following steps:
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1) dom0: xl mem-max <domU> <maxmem>
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where <maxmem> is >= requested memory size,
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2) dom0: xl mem-set <domU> <memory>
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where <memory> is requested memory size; alternatively memory
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could be added by writing proper value to
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/sys/devices/system/xen_memory/xen_memory0/target or
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/sys/devices/system/xen_memory/xen_memory0/target_kb on dumU,
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3) domU: for i in /sys/devices/system/memory/memory*/state; do \
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[ "`cat "$i"`" = offline ] && echo online > "$i"; done
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Memory could be onlined automatically on domU by adding following line to udev rules:
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SUBSYSTEM=="memory", ACTION=="add", RUN+="/bin/sh -c '[ -f /sys$devpath/state ] && echo online > /sys$devpath/state'"
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In that case step 3 should be omitted.
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config XEN_SCRUB_PAGES
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bool "Scrub pages before returning them to system"
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depends on XEN_BALLOON
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default y
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help
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Scrub pages before returning them to the system for reuse by
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other domains. This makes sure that any confidential data
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is not accidentally visible to other domains. Is it more
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secure, but slightly less efficient.
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If in doubt, say yes.
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config XEN_DEV_EVTCHN
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tristate "Xen /dev/xen/evtchn device"
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default y
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help
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The evtchn driver allows a userspace process to triger event
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channels and to receive notification of an event channel
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firing.
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If in doubt, say yes.
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config XEN_BACKEND
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bool "Backend driver support"
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depends on XEN_DOM0
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default y
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help
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Support for backend device drivers that provide I/O services
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to other virtual machines.
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config XENFS
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tristate "Xen filesystem"
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select XEN_PRIVCMD
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default y
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help
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The xen filesystem provides a way for domains to share
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information with each other and with the hypervisor.
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For example, by reading and writing the "xenbus" file, guests
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may pass arbitrary information to the initial domain.
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If in doubt, say yes.
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config XEN_COMPAT_XENFS
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bool "Create compatibility mount point /proc/xen"
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depends on XENFS
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default y
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help
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The old xenstore userspace tools expect to find "xenbus"
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under /proc/xen, but "xenbus" is now found at the root of the
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xenfs filesystem. Selecting this causes the kernel to create
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the compatibility mount point /proc/xen if it is running on
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a xen platform.
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If in doubt, say yes.
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config XEN_SYS_HYPERVISOR
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bool "Create xen entries under /sys/hypervisor"
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depends on SYSFS
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select SYS_HYPERVISOR
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default y
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help
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Create entries under /sys/hypervisor describing the Xen
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hypervisor environment. When running native or in another
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virtual environment, /sys/hypervisor will still be present,
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but will have no xen contents.
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config XEN_XENBUS_FRONTEND
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tristate
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config XEN_GNTDEV
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tristate "userspace grant access device driver"
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depends on XEN
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default m
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select MMU_NOTIFIER
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help
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Allows userspace processes to use grants.
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config XEN_GRANT_DEV_ALLOC
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tristate "User-space grant reference allocator driver"
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depends on XEN
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default m
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help
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Allows userspace processes to create pages with access granted
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to other domains. This can be used to implement frontend drivers
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or as part of an inter-domain shared memory channel.
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config SWIOTLB_XEN
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def_bool y
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depends on PCI
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select SWIOTLB
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config XEN_TMEM
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bool
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default y if (CLEANCACHE || FRONTSWAP)
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help
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Shim to interface in-kernel Transcendent Memory hooks
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(e.g. cleancache and frontswap) to Xen tmem hypercalls.
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config XEN_PCIDEV_BACKEND
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tristate "Xen PCI-device backend driver"
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depends on PCI && X86 && XEN
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depends on XEN_BACKEND
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default m
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help
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The PCI device backend driver allows the kernel to export arbitrary
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PCI devices to other guests. If you select this to be a module, you
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will need to make sure no other driver has bound to the device(s)
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you want to make visible to other guests.
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The parameter "passthrough" allows you specify how you want the PCI
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devices to appear in the guest. You can choose the default (0) where
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PCI topology starts at 00.00.0, or (1) for passthrough if you want
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the PCI devices topology appear the same as in the host.
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The "hide" parameter (only applicable if backend driver is compiled
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into the kernel) allows you to bind the PCI devices to this module
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from the default device drivers. The argument is the list of PCI BDFs:
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xen-pciback.hide=(03:00.0)(04:00.0)
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If in doubt, say m.
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config XEN_PRIVCMD
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tristate
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depends on XEN
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default m
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config XEN_ACPI_PROCESSOR
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tristate "Xen ACPI processor"
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depends on XEN && X86 && ACPI_PROCESSOR
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default y if (X86_ACPI_CPUFREQ = y || X86_POWERNOW_K8 = y)
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default m if (X86_ACPI_CPUFREQ = m || X86_POWERNOW_K8 = m)
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help
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This ACPI processor uploads Power Management information to the Xen hypervisor.
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To do that the driver parses the Power Management data and uploads said
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information to the Xen hypervisor. Then the Xen hypervisor can select the
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proper Cx and Pxx states. It also registers itslef as the SMM so that
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other drivers (such as ACPI cpufreq scaling driver) will not load.
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To compile this driver as a module, choose M here: the
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module will be called xen_acpi_processor If you do not know what to choose,
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select M here. If the CPUFREQ drivers are built in, select Y here.
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endmenu
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