* pci/aer:
  PCI/AER: Fix aer_probe() kernel-doc comment
  PCI/AER: Cache capability position
  PCI/AER: Avoid memory allocation in interrupt handling path
  ACPI / APEI: Send correct severity to calculate AER severity
  PCI/AER: Remove duplicate AER severity translation
  PCI/AER: Remove aerdriver.forceload kernel parameter
  PCI/AER: Remove aerdriver.nosourceid kernel parameter
  x86/PCI: VMD: Add quirk for AER to ignore source ID
  PCI/AER: Add bus flag to skip source ID matching

Conflicts:
	drivers/pci/probe.c

0516c8bc ("PCI: PCIe portdrv: Simplily probe callback of service
drivers") removed the "id" argument of aer_probe() but neglected to remove
the kernel-doc comment.  Update the comment.

[bhelgaas: changelog]
Signed-off-by: Cao jin <caoj.fnst@cn.fujitsu.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

Save the position of the error reporting capability so it doesn't need to
be rediscovered during error handling.
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: Lukas Wunner <lukas@wunner.de>

When handling AER events, we previously allocated a struct aer_err_info,
processed the error, and freed the struct.  But aer_isr_one_error() is
serialized by rpc_mutex, so we never need more than one copy of the struct,
and the struct is only about 70 bytes, so we're not saving much by
allocating it dynamically.

Embed a struct aer_err_info directly in struct aer_rpc, which is allocated
at probe-time by aer_probe().

[bhelgaas: changelog]
Suggested-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Jon Derrick <jonathan.derrick@intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

Currently the AER severity is calculated by calling cper_severity_to_aer(),
but the parameter sent is actually the GHES severity.  This causes the AER
severity to be incorrect.

Fix the parameter to be the CPER severity instead of the GHES severity.
Signed-off-by: Tyler Baicar <tbaicar@codeaurora.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Borislav Petkov <bp@suse.de>

Currently the AER severity is being translated twice in the code flow for
PCIe errors.  It is first translated in ghes_do_proc() before calling into
the AER driver.  Then it is translated again when the AER driver calls
cper_print_aer().  This causes the severity that is used in
cper_print_aer() to be incorrect.

Remove the second translation that is in cper_print_aer() since this
function is already receiving the correct AER severity.
Signed-off-by: Tyler Baicar <tbaicar@codeaurora.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Borislav Petkov <bp@suse.de>

Per the PCI Firmware spec, r3.0, sec 4.5.1, on ACPI systems, the OS must
not use AER unless _OSC is present and _OSC grants AER control to the OS.
The aerdriver.forceload kernel parameter was a way to enable Linux AER
support on ACPI systems that lack _OSC or fail to grant control the the OS.

Enabling Linux AER support when the firmware doesn't want us to is a recipe
for problems, e.g., the firmware might be handling AER itself.

Remove the aerdriver.forceload kernel parameter and related supporting
code.
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

The aerdriver.nosourceid kernel parameter was intended for working around
broken chipsets don't supply the source ID for AER events.  We recently
added PCI_BUS_FLAGS_NO_AERSID, which can be set by quirks for the same
purpose.

Remove the aerdriver.nosourceid kernel parameter.  For anything other than
debugging, asking users to find and use kernel parameters is a poor user
experience.  Instead, we should add PCI_BUS_FLAGS_NO_AERSID quirks for any
hardware that needs it.
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

VMD root ports change all source ids to the VMD device ID.  To find the
sender of the AER notification, we need to scan all child devices for the
AER sender, rather than relying on the source ID from the message.
Signed-off-by: Jon Derrick <jonathan.derrick@intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

Allow root port buses to choose to skip source id matching when finding the
faulting device.  Certain root port devices may return an incorrect source
ID and recommend to scan child device registers for AER notifications.
Signed-off-by: Jon Derrick <jonathan.derrick@intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

* pci/ptm:
  PCI: Add PTM clock granularity information
  PCI: Add pci_enable_ptm() for drivers to enable PTM on endpoints
  PCI: Add Precision Time Measurement (PTM) support

* pci/demodularize:
  PCI: pciehp: Make explicitly non-modular
  PCI: hotplug: Make core explicitly non-modular
  PCI: xilinx-nwl: Make explicitly non-modular
  PCI: xilinx: Make explicitly non-modular
  PCI: qcom: Make explicitly non-modular
  PCI: dra7xx: Make explicitly non-modular
  PCI/AER: Make explicitly non-modular
  PCI/PME: Make explicitly non-modular
  PCI: Make DPC explicitly non-modular
  PCI: generic: Make explicitly non-modular
  PCI: exynos: Make explicitly non-modular
  PCI: designware: Make explicitly non-modular
  PCI: spear: Make explicitly non-modular
  PCI: portdrv: Make explicitly non-modular
  PCI: imx6: Make explicitly non-modular
  PCI: altera: Make explicitly non-modular
  PCI: altera: Make MSI explicitly non-modular

The PTM Control register (PCIe r3.1, sec 7.32.3) contains an Effective
Granularity field:

  This provides information relating to the expected accuracy of the PTM
  clock, but does not otherwise affect the PTM mechanism.

Set the Effective Granularity based on the PTM Root and any intervening PTM
Time Sources.

This does not set Effective Granularity for Root Complex Integrated
Endpoints because I don't know how to figure out clock granularity for
them.  The spec says:

  ... system software must set [Effective Granularity] to the value
  reported in the Local Clock Granularity field by the associated PTM
  Time Source.

but I don't know how to identify the associated PTM Time Source.  Normally
it's the upstream bridge, but an integrated endpoint has no upstream
bridge.
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

This code is not being built as a module by anyone:

  obj-$(CONFIG_HOTPLUG_PCI_PCIE)          += pciehp.o
  pciehp-objs                             := pciehp_core.o   \

  drivers/pci/pcie/Kconfig:config HOTPLUG_PCI_PCIE
  drivers/pci/pcie/Kconfig:  bool "PCI Express Hotplug driver"

Remove uses of MODULE_DESCRIPTION(), MODULE_AUTHOR(), MODULE_LICENSE(),
etc., so that when reading the driver there is no doubt it is builtin-only.
The information is preserved in comments at the top of the file.

Note that for non-modular code, module_init() translates to
device_initcall().  One could argue that we should use subsys_initcall()
here, but for now we stick with runtime equivalence.

We delete module.h but we keep the moduleparam.h include, since we are
keeping the module_param() that the file has as-is for now.
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: Kristen Carlson Accardi <kristen@linux.intel.com>

This code is not being built as a module by anyone:

  obj-$(CONFIG_HOTPLUG_PCI)           += pci_hotplug.o
  [...]
  pci_hotplug-objs                    := pci_hotplug_core.o

  drivers/pci/hotplug/Kconfig:menuconfig HOTPLUG_PCI
  drivers/pci/hotplug/Kconfig:  bool "Support for PCI Hotplug"

Remove uses of MODULE_DESCRIPTION(), MODULE_AUTHOR(), MODULE_LICENSE(),
etc., so that when reading the driver there is no doubt it is builtin-only.
The information is preserved in comments at the top of the file.

Remove orphaned exit function in cpci_hotplug_core.c.

Note that for non-modular code, module_init() translates to
device_initcall().  One could argue that we should use subsys_initcall()
here, but for now we stick with runtime equivalence.

We would delete module.h and just keep the moduleparam.h include (since the
file does use module_param), but there is a try_module_get and module_put
pairing that prevents us from doing that.

[bhelgaas: changelog]
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: Scott Murray <scott@spiteful.org>
CC: Kristen Carlson Accardi <kristen@linux.intel.com>

This code is not being built as a module by anyone:

  drivers/pci/host/Kconfig:config PCIE_XILINX_NWL
  drivers/pci/host/Kconfig:  bool "NWL PCIe Core"

Remove uses of MODULE_DESCRIPTION(), MODULE_AUTHOR(), MODULE_LICENSE(),
etc., so that when reading the driver there is no doubt it is builtin-only.
The information is preserved in comments at the top of the file.

Explicitly disallow driver unbind, since that doesn't have a sensible use
case anyway, and it allows us to drop the ".remove" code for non-modular
drivers.  Delete several functions only used by the remove function.

Note that for non-modular code, builtin_platform_driver() uses the same
init level priority as module_platform_driver(), so this doesn't change
init ordering.

[bhelgaas: changelog]
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: Michal Simek <michal.simek@xilinx.com>
CC: "Sören Brinkmann" <soren.brinkmann@xilinx.com>
CC: Marc Zyngier <marc.zyngier@arm.com>
CC: Bharat Kumar Gogada <bharat.kumar.gogada@xilinx.com>

This code is not being built as a module by anyone:

  drivers/pci/host/Kconfig:config PCIE_XILINX
  drivers/pci/host/Kconfig:  bool "Xilinx AXI PCIe host bridge support"

Remove uses of MODULE_DESCRIPTION(), MODULE_AUTHOR(), MODULE_LICENSE(),
etc., so that when reading the driver there is no doubt it is builtin-only.
The information is preserved in comments at the top of the file.

Note that for non-modular code, builtin_platform_driver() uses the same
init level priority as module_platform_driver(), so this doesn't change
init ordering.

[bhelgaas: changelog]
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: Michal Simek <michal.simek@xilinx.com>
CC: "Sören Brinkmann" <soren.brinkmann@xilinx.com>

This code is not being built as a module by anyone:

  drivers/pci/host/Kconfig:config PCIE_QCOM
  drivers/pci/host/Kconfig:  bool "Qualcomm PCIe controller"

Remove uses of MODULE_DESCRIPTION(), MODULE_AUTHOR(), MODULE_LICENSE(),
etc., so that when reading the driver there is no doubt it is builtin-only.
The information is preserved in comments at the top of the file.

Note that for non-modular code, MODULE_DEVICE_TABLE is a no-op and
builtin_platform_driver() uses the same init level priority as
module_platform_driver(), so this doesn't change init ordering.

Explicitly disallow driver unbind, since that doesn't have a sensible use
case anyway, and it allows us to drop the ".remove" code for non-modular
drivers.

[bhelgaas: changelog]
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: Stanimir Varbanov <svarbanov@mm-sol.com>

This code is not being built as a module by anyone:

  drivers/pci/host/Kconfig:config PCI_DRA7XX
  drivers/pci/host/Kconfig:  bool "TI DRA7xx PCIe controller"

Remove uses of MODULE_DESCRIPTION(), MODULE_AUTHOR(), MODULE_LICENSE(),
etc., so that when reading the driver there is no doubt it is builtin-only.
The information is preserved in comments at the top of the file.

Note that for non-modular code, MODULE_DEVICE_TABLE is a no-op and
builtin_platform_driver_probe() uses the same init level priority as
module_platform_driver_probe(), so this doesn't change init ordering.

Explicitly disallow driver unbind, since that doesn't have a sensible use
case anyway, and it allows us to drop the ".remove" code for non-modular
drivers.

[bhelgaas: changelog]
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: Kishon Vijay Abraham I <kishon@ti.com>

This code is not being built as a module by anyone:

  obj-$(CONFIG_PCIEAER) += aerdriver.o
  aerdriver-objs := aerdrv_errprint.o aerdrv_core.o aerdrv.o

  drivers/pci/pcie/aer/Kconfig:config PCIEAER
  drivers/pci/pcie/aer/Kconfig:  bool "Root Port Advanced Error Reporting support"

Remove uses of MODULE_DESCRIPTION(), MODULE_AUTHOR(), MODULE_LICENSE(),
etc., so that when reading the driver there is no doubt it is builtin-only.
The information is preserved in comments at the top of the file.

Note that for non-modular code, module_init() translates to
device_initcall().

[bhelgaas: changelog]
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: Tom Long Nguyen <tom.l.nguyen@intel.com>

This code is not being built as a module by anyone:

  config PCIE_PME
        def_bool y
        depends on PCIEPORTBUS && PM

Remove traces of modularity so that when reading the driver there is no
doubt it is builtin-only.

Also delete the .remove function, since that doesn't seem to have a
sensible use case.  With "normal" endpoint drivers, we have in the past set
the suppress_bind_attrs bit to make it clear that the use of ".remove" in a
builtin driver was deleted, but here for PCI, it seems overkill to jump
through the pcie_port_service_driver and into the struct device_driver in
order to finally try and do something similar with the bind setting.

Note that for non-modular code, module_init() translates to
device_initcall().
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

This code is not being built as a module by anyone:

  drivers/pci/pcie/Kconfig:config PCIE_DPC
  drivers/pci/pcie/Kconfig:  bool "PCIe Downstream Port Containment support"

Remove uses of MODULE_DESCRIPTION(), MODULE_AUTHOR(), MODULE_LICENSE(),
etc., so that when reading the driver there is no doubt it is builtin-only.
The information is preserved in comments at the top of the file.

Note that for non-modular code, module_init() translates to
device_initcall().

[bhelgaas: changelog]
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: Keith Busch <keith.busch@intel.com>
CC: Mika Westerberg <mika.westerberg@linux.intel.com>

This code is not being built as a module by anyone:

  drivers/pci/host/Kconfig:config PCI_HOST_COMMON
  drivers/pci/host/Kconfig:  bool

Remove uses of MODULE_DESCRIPTION(), MODULE_AUTHOR(), MODULE_LICENSE(),
etc., so that when reading the driver there is no doubt it is builtin-only.
The information is preserved in comments at the top of the file.
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: Will Deacon <will.deacon@arm.com>

This code is not being built as a module by anyone:

  drivers/pci/host/Kconfig:config PCI_EXYNOS
  drivers/pci/host/Kconfig:  bool "Samsung Exynos PCIe controller"

Remove uses of MODULE_DESCRIPTION(), MODULE_AUTHOR(), MODULE_LICENSE(),
etc., so that when reading the driver there is no doubt it is builtin-only.
The information is preserved in comments at the top of the file.

Note that for non-modular code, MODULE_DEVICE_TABLE is a no-op.

[bhelgaas: changelog]
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Krzysztof Kozlowski <krzk@kernel.org>
CC: Jingoo Han <jingoohan1@gmail.com>
CC: Kukjin Kim <kgene@kernel.org>

This code is not being built as a module by anyone:

  drivers/pci/host/Kconfig:config PCIE_DW
  drivers/pci/host/Kconfig:  bool

Remove uses of MODULE_DESCRIPTION(), MODULE_AUTHOR(), MODULE_LICENSE(),
etc., so that when reading the driver there is no doubt it is builtin-only.
The information is preserved in comments at the top of the file.

[bhelgaas: changelog]
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: Jingoo Han <jingoohan1@gmail.com>
CC: Pratyush Anand <pratyush.anand@gmail.com>

This code is not being built as a module by anyone:

  drivers/pci/host/Kconfig:config PCIE_SPEAR13XX
  drivers/pci/host/Kconfig:  bool "STMicroelectronics SPEAr PCIe controller"

Remove uses of MODULE_DESCRIPTION(), MODULE_AUTHOR(), MODULE_LICENSE(),
etc., so that when reading the driver there is no doubt it is builtin-only.
The information is preserved in comments at the top of the file.

Note that for non-modular code, MODULE_DEVICE_TABLE is a no-op and
module_init() translates to device_initcall().

[bhelgaas: changelog]
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: Pratyush Anand <pratyush.anand@gmail.com>

This code is not being built as a module by anyone:

  pcieportdrv-y               := portdrv_core.o portdrv_pci.o portdrv_bus.o
  obj-$(CONFIG_PCIEPORTBUS)   += pcieportdrv.o

  drivers/pci/pcie/Kconfig:config PCIEPORTBUS
  drivers/pci/pcie/Kconfig:  bool "PCI Express Port Bus support"

Remove uses of MODULE_DESCRIPTION(), MODULE_AUTHOR(), MODULE_LICENSE(),
etc., so that when reading the driver there is no doubt it is builtin-only.
The information is preserved in comments at the top of the file.

Note that for non-modular code, MODULE_DEVICE_TABLE is a no-op and
module_init() translates to device_initcall().

[bhelgaas: changelog, remove unused DRIVER_* macros]
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: Tom Long Nguyen <tom.l.nguyen@intel.com>

This code is not being built as a module by anyone:

  drivers/pci/host/Kconfig:config PCI_IMX6
  drivers/pci/host/Kconfig:  bool "Freescale i.MX6 PCIe controller"

Remove uses of MODULE_DESCRIPTION(), MODULE_AUTHOR(), MODULE_LICENSE(),
etc., so that when reading the driver there is no doubt it is builtin-only.
The information is preserved in comments at the top of the file.

Note that for non-modular code, MODULE_DEVICE_TABLE is a no-op and
module_init() translates to device_initcall().

[bhelgaas: changelog]
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: Richard Zhu <Richard.Zhu@freescale.com>
CC: Lucas Stach <l.stach@pengutronix.de>

This code is not being built as a module by anyone:

  drivers/pci/host/Kconfig:config PCIE_ALTERA
  drivers/pci/host/Kconfig:  bool "Altera PCIe controller"

Remove uses of MODULE_DESCRIPTION(), MODULE_AUTHOR(), MODULE_LICENSE(),
etc., so that when reading the driver there is no doubt it is builtin-only.
The information is preserved in comments at the top of the file.

Note that for non-modular code, MODULE_DEVICE_TABLE is a no-op and
module_init() translates to device_initcall().

[bhelgaas: changelog]
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: Ley Foon Tan <lftan@altera.com>

This code is not being built as a module by anyone:

  drivers/pci/host/Kconfig:config PCIE_ALTERA_MSI
  drivers/pci/host/Kconfig:  bool "Altera PCIe MSI feature"

Remove uses of MODULE_DESCRIPTION(), MODULE_AUTHOR(), MODULE_LICENSE(),
etc., so that when reading the driver there is no doubt it is builtin-only.
The information is preserved in comments at the top of the file.

[bhelgaas: changelog]
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: Ley Foon Tan <lftan@altera.com>

Add an pci_enable_ptm() interface so drivers can enable PTM.

The PCI core enables PTM on PTM Roots and switches automatically, but we
don't enable PTM on endpoints unless a driver requests it.
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

Add Precision Time Measurement (PTM) support (see PCIe r3.1, sec 6.22).

Enable PTM on PTM Root devices and switch ports.  This does not enable PTM
on endpoints.

There currently are no PTM-capable devices on the market, but it is
expected to be supported by the Intel Apollo Lake platform.

[bhelgaas: complete rework]
Signed-off-by: Jonathan Yong <jonathan.yong@intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

Pull more block fixes from Jens Axboe:
 "As mentioned in the pull the other day, a few more fixes for this
  round, all related to the bio op changes in this series.

  Two fixes, and then a cleanup, renaming bio->bi_rw to bio->bi_opf.  I
  wanted to do that change right after or right before -rc1, so that
  risk of conflict was reduced.  I just rebased the series on top of
  current master, and no new ->bi_rw usage has snuck in"

* 'for-linus' of git://git.kernel.dk/linux-block:
  block: rename bio bi_rw to bi_opf
  target: iblock_execute_sync_cache() should use bio_set_op_attrs()
  mm: make __swap_writepage() use bio_set_op_attrs()
  block/mm: make bdev_ops->rw_page() take a bool for read/write

Pull drm zpos property support from Dave Airlie:
 "This tree was waiting on some media stuff I hadn't had time to get a
  stable branchpoint off, so I just waited until it was all in your tree
  first.

  It's been around a bit on the list and shouldn't affect anything
  outside adding the generic API and moving some ARM drivers to using
  it"

* tag 'drm-for-v4.8-zpos' of git://people.freedesktop.org/~airlied/linux:
  drm: rcar: use generic code for managing zpos plane property
  drm/exynos: use generic code for managing zpos plane property
  drm: sti: use generic zpos for plane
  drm: add generic zpos property

Since commit 63a4cc24, bio->bi_rw contains flags in the lower
portion and the op code in the higher portions. This means that
old code that relies on manually setting bi_rw is most likely
going to be broken. Instead of letting that brokeness linger,
rename the member, to force old and out-of-tree code to break
at compile time instead of at runtime.

No intended functional changes in this commit.
Signed-off-by: Jens Axboe <axboe@fb.com>

The original commit missed this function, it needs to mark it a
write flush.

Cc: Mike Christie <mchristi@redhat.com>
Fixes: e742fc32 ("target: use bio op accessors")
Signed-off-by: Jens Axboe <axboe@fb.com>

Cleaner than manipulating bio->bi_rw flags directly.
Signed-off-by: Jens Axboe <axboe@fb.com>

Commit abf54548 changed it from an 'rw' flags type to the
newer ops based interface, but now we're effectively leaking
some bdev internals to the rest of the kernel. Since we only
care about whether it's a read or a write at that level, just
pass in a bool 'is_write' parameter instead.

Then we can also move op_is_write() and friends back under
CONFIG_BLOCK protection.
Reviewed-by: Mike Christie <mchristi@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

Pull documentation fixes from Jonathan Corbet:
 "Three fixes for the docs build, including removing an annoying warning
  on 'make help' if sphinx isn't present"

* tag 'doc-4.8-fixes' of git://git.lwn.net/linux:
  DocBook: use DOCBOOKS="" to ignore DocBooks instead of IGNORE_DOCBOOKS=1
  Documenation: update cgroup's document path
  Documentation/sphinx: do not warn about missing tools in 'make help'