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# SPDX-License-Identifier: GPL-2.0-only
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config DAX_DRIVER
select DAX
bool
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menuconfig DAX
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tristate "DAX: direct access to differentiated memory"
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select SRCU
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default m if NVDIMM_DAX
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if DAX
config DEV_DAX
tristate "Device DAX: direct access mapping device"
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depends on TRANSPARENT_HUGEPAGE
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help
Support raw access to differentiated (persistence, bandwidth,
latency...) memory via an mmap(2) capable character
device. Platform firmware or a device driver may identify a
platform memory resource that is differentiated from the
baseline memory pool. Mappings of a /dev/daxX.Y device impose
restrictions that make the mapping behavior deterministic.
config DEV_DAX_PMEM
tristate "PMEM DAX: direct access to persistent memory"
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depends on LIBNVDIMM && NVDIMM_DAX && DEV_DAX
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default DEV_DAX
help
Support raw access to persistent memory. Note that this
driver consumes memory ranges allocated and exported by the
libnvdimm sub-system.
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Say M if unsure
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config DEV_DAX_HMEM
tristate "HMEM DAX: direct access to 'specific purpose' memory"
depends on EFI_SOFT_RESERVE
default DEV_DAX
help
EFI 2.8 platforms, and others, may advertise 'specific purpose'
memory. For example, a high bandwidth memory pool. The
indication from platform firmware is meant to reserve the
memory from typical usage by default. This driver creates
device-dax instances for these memory ranges, and that also
enables the possibility to assign them to the DEV_DAX_KMEM
driver to override the reservation and add them to kernel
"System RAM" pool.
Say M if unsure.
device-dax: "Hotplug" persistent memory for use like normal RAM
This is intended for use with NVDIMMs that are physically persistent
(physically like flash) so that they can be used as a cost-effective
RAM replacement. Intel Optane DC persistent memory is one
implementation of this kind of NVDIMM.
Currently, a persistent memory region is "owned" by a device driver,
either the "Direct DAX" or "Filesystem DAX" drivers. These drivers
allow applications to explicitly use persistent memory, generally
by being modified to use special, new libraries. (DIMM-based
persistent memory hardware/software is described in great detail
here: Documentation/nvdimm/nvdimm.txt).
However, this limits persistent memory use to applications which
*have* been modified. To make it more broadly usable, this driver
"hotplugs" memory into the kernel, to be managed and used just like
normal RAM would be.
To make this work, management software must remove the device from
being controlled by the "Device DAX" infrastructure:
echo dax0.0 > /sys/bus/dax/drivers/device_dax/unbind
and then tell the new driver that it can bind to the device:
echo dax0.0 > /sys/bus/dax/drivers/kmem/new_id
After this, there will be a number of new memory sections visible
in sysfs that can be onlined, or that may get onlined by existing
udev-initiated memory hotplug rules.
This rebinding procedure is currently a one-way trip. Once memory
is bound to "kmem", it's there permanently and can not be
unbound and assigned back to device_dax.
The kmem driver will never bind to a dax device unless the device
is *explicitly* bound to the driver. There are two reasons for
this: One, since it is a one-way trip, it can not be undone if
bound incorrectly. Two, the kmem driver destroys data on the
device. Think of if you had good data on a pmem device. It
would be catastrophic if you compile-in "kmem", but leave out
the "device_dax" driver. kmem would take over the device and
write volatile data all over your good data.
This inherits any existing NUMA information for the newly-added
memory from the persistent memory device that came from the
firmware. On Intel platforms, the firmware has guarantees that
require each socket's persistent memory to be in a separate
memory-only NUMA node. That means that this patch is not expected
to create NUMA nodes, but will simply hotplug memory into existing
nodes.
Because NUMA nodes are created, the existing NUMA APIs and tools
are sufficient to create policies for applications or memory areas
to have affinity for or an aversion to using this memory.
There is currently some metadata at the beginning of pmem regions.
The section-size memory hotplug restrictions, plus this small
reserved area can cause the "loss" of a section or two of capacity.
This should be fixable in follow-on patches. But, as a first step,
losing 256MB of memory (worst case) out of hundreds of gigabytes
is a good tradeoff vs. the required code to fix this up precisely.
This calculation is also the reason we export
memory_block_size_bytes().
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Keith Busch <keith.busch@intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Ross Zwisler <zwisler@kernel.org>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: linux-nvdimm@lists.01.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org
Cc: Huang Ying <ying.huang@intel.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Yaowei Bai <baiyaowei@cmss.chinamobile.com>
Cc: Takashi Iwai <tiwai@suse.de>
Cc: Jerome Glisse <jglisse@redhat.com>
Reviewed-by: Vishal Verma <vishal.l.verma@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2019-02-25 21:57:40 +03:00
config DEV_DAX_KMEM
tristate "KMEM DAX: volatile-use of persistent memory"
default DEV_DAX
depends on DEV_DAX
depends on MEMORY_HOTPLUG # for add_memory() and friends
help
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Support access to persistent, or other performance
differentiated memory as if it were System RAM. This allows
easier use of persistent memory by unmodified applications, or
adds core kernel memory services to heterogeneous memory types
(HMEM) marked "reserved" by platform firmware.
device-dax: "Hotplug" persistent memory for use like normal RAM
This is intended for use with NVDIMMs that are physically persistent
(physically like flash) so that they can be used as a cost-effective
RAM replacement. Intel Optane DC persistent memory is one
implementation of this kind of NVDIMM.
Currently, a persistent memory region is "owned" by a device driver,
either the "Direct DAX" or "Filesystem DAX" drivers. These drivers
allow applications to explicitly use persistent memory, generally
by being modified to use special, new libraries. (DIMM-based
persistent memory hardware/software is described in great detail
here: Documentation/nvdimm/nvdimm.txt).
However, this limits persistent memory use to applications which
*have* been modified. To make it more broadly usable, this driver
"hotplugs" memory into the kernel, to be managed and used just like
normal RAM would be.
To make this work, management software must remove the device from
being controlled by the "Device DAX" infrastructure:
echo dax0.0 > /sys/bus/dax/drivers/device_dax/unbind
and then tell the new driver that it can bind to the device:
echo dax0.0 > /sys/bus/dax/drivers/kmem/new_id
After this, there will be a number of new memory sections visible
in sysfs that can be onlined, or that may get onlined by existing
udev-initiated memory hotplug rules.
This rebinding procedure is currently a one-way trip. Once memory
is bound to "kmem", it's there permanently and can not be
unbound and assigned back to device_dax.
The kmem driver will never bind to a dax device unless the device
is *explicitly* bound to the driver. There are two reasons for
this: One, since it is a one-way trip, it can not be undone if
bound incorrectly. Two, the kmem driver destroys data on the
device. Think of if you had good data on a pmem device. It
would be catastrophic if you compile-in "kmem", but leave out
the "device_dax" driver. kmem would take over the device and
write volatile data all over your good data.
This inherits any existing NUMA information for the newly-added
memory from the persistent memory device that came from the
firmware. On Intel platforms, the firmware has guarantees that
require each socket's persistent memory to be in a separate
memory-only NUMA node. That means that this patch is not expected
to create NUMA nodes, but will simply hotplug memory into existing
nodes.
Because NUMA nodes are created, the existing NUMA APIs and tools
are sufficient to create policies for applications or memory areas
to have affinity for or an aversion to using this memory.
There is currently some metadata at the beginning of pmem regions.
The section-size memory hotplug restrictions, plus this small
reserved area can cause the "loss" of a section or two of capacity.
This should be fixable in follow-on patches. But, as a first step,
losing 256MB of memory (worst case) out of hundreds of gigabytes
is a good tradeoff vs. the required code to fix this up precisely.
This calculation is also the reason we export
memory_block_size_bytes().
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Keith Busch <keith.busch@intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Ross Zwisler <zwisler@kernel.org>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: linux-nvdimm@lists.01.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org
Cc: Huang Ying <ying.huang@intel.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Yaowei Bai <baiyaowei@cmss.chinamobile.com>
Cc: Takashi Iwai <tiwai@suse.de>
Cc: Jerome Glisse <jglisse@redhat.com>
Reviewed-by: Vishal Verma <vishal.l.verma@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2019-02-25 21:57:40 +03:00
To use this feature, a DAX device must be unbound from the
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device_dax driver and bound to this kmem driver on each boot.
device-dax: "Hotplug" persistent memory for use like normal RAM
This is intended for use with NVDIMMs that are physically persistent
(physically like flash) so that they can be used as a cost-effective
RAM replacement. Intel Optane DC persistent memory is one
implementation of this kind of NVDIMM.
Currently, a persistent memory region is "owned" by a device driver,
either the "Direct DAX" or "Filesystem DAX" drivers. These drivers
allow applications to explicitly use persistent memory, generally
by being modified to use special, new libraries. (DIMM-based
persistent memory hardware/software is described in great detail
here: Documentation/nvdimm/nvdimm.txt).
However, this limits persistent memory use to applications which
*have* been modified. To make it more broadly usable, this driver
"hotplugs" memory into the kernel, to be managed and used just like
normal RAM would be.
To make this work, management software must remove the device from
being controlled by the "Device DAX" infrastructure:
echo dax0.0 > /sys/bus/dax/drivers/device_dax/unbind
and then tell the new driver that it can bind to the device:
echo dax0.0 > /sys/bus/dax/drivers/kmem/new_id
After this, there will be a number of new memory sections visible
in sysfs that can be onlined, or that may get onlined by existing
udev-initiated memory hotplug rules.
This rebinding procedure is currently a one-way trip. Once memory
is bound to "kmem", it's there permanently and can not be
unbound and assigned back to device_dax.
The kmem driver will never bind to a dax device unless the device
is *explicitly* bound to the driver. There are two reasons for
this: One, since it is a one-way trip, it can not be undone if
bound incorrectly. Two, the kmem driver destroys data on the
device. Think of if you had good data on a pmem device. It
would be catastrophic if you compile-in "kmem", but leave out
the "device_dax" driver. kmem would take over the device and
write volatile data all over your good data.
This inherits any existing NUMA information for the newly-added
memory from the persistent memory device that came from the
firmware. On Intel platforms, the firmware has guarantees that
require each socket's persistent memory to be in a separate
memory-only NUMA node. That means that this patch is not expected
to create NUMA nodes, but will simply hotplug memory into existing
nodes.
Because NUMA nodes are created, the existing NUMA APIs and tools
are sufficient to create policies for applications or memory areas
to have affinity for or an aversion to using this memory.
There is currently some metadata at the beginning of pmem regions.
The section-size memory hotplug restrictions, plus this small
reserved area can cause the "loss" of a section or two of capacity.
This should be fixable in follow-on patches. But, as a first step,
losing 256MB of memory (worst case) out of hundreds of gigabytes
is a good tradeoff vs. the required code to fix this up precisely.
This calculation is also the reason we export
memory_block_size_bytes().
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Keith Busch <keith.busch@intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Ross Zwisler <zwisler@kernel.org>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: linux-nvdimm@lists.01.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org
Cc: Huang Ying <ying.huang@intel.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Yaowei Bai <baiyaowei@cmss.chinamobile.com>
Cc: Takashi Iwai <tiwai@suse.de>
Cc: Jerome Glisse <jglisse@redhat.com>
Reviewed-by: Vishal Verma <vishal.l.verma@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2019-02-25 21:57:40 +03:00
Say N if unsure.
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config DEV_DAX_PMEM_COMPAT
tristate "PMEM DAX: support the deprecated /sys/class/dax interface"
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depends on m && DEV_DAX_PMEM=m
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default DEV_DAX_PMEM
help
Older versions of the libdaxctl library expect to find all
device-dax instances under /sys/class/dax. If libdaxctl in
your distribution is older than v58 say M, otherwise say N.
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endif
