The DAX drivers were missing sysfs ABI documentation entirely. Add this
missing documentation for the sysfs ABI for DAX regions and Dax devices
in patch 1. Add a new ABI for toggling memmap_on_memory semantics in
patch 2.
The missing ABI was spotted in [1], this series is a split of the new
ABI additions behind the initial documentation creation.
[1]: https://lore.kernel.org/linux-cxl/[email protected]/
Changes in v3:
- Fix typo in ABI docs (Zhijian Li)
- Add kernel config and module parameter dependencies to the ABI docs
entry (David Hildenbrand)
- Ensure kmem isn't active when setting the sysfs attribute (Ying
Huang)
- Simplify returning from memmap_on_memory_store()
- Link to v2: https://lore.kernel.org/r/[email protected]
Changes in v2:
- Fix CC lists, patch 1/2 didn't get sent correctly in v1
- Link to v1: https://lore.kernel.org/r/[email protected]
---
Vishal Verma (2):
Documentatiion/ABI: Add ABI documentation for sys-bus-dax
dax: add a sysfs knob to control memmap_on_memory behavior
drivers/dax/bus.c | 47 +++++++++
Documentation/ABI/testing/sysfs-bus-dax | 168 ++++++++++++++++++++++++++++++++
2 files changed, 215 insertions(+)
---
base-commit: c4e1ccfad42352918810802095a8ace8d1c744c9
change-id: 20231025-vv-dax_abi-17a219c46076
Best regards,
--
Vishal Verma <[email protected]>
Add the missing sysfs ABI documentation for the device DAX subsystem.
Various ABI attributes under this have been present since v5.1, and more
have been added over time. In preparation for adding a new attribute,
add this file with the historical details.
Cc: Dan Williams <[email protected]>
Signed-off-by: Vishal Verma <[email protected]>
---
Documentation/ABI/testing/sysfs-bus-dax | 151 ++++++++++++++++++++++++++++++++
1 file changed, 151 insertions(+)
diff --git a/Documentation/ABI/testing/sysfs-bus-dax b/Documentation/ABI/testing/sysfs-bus-dax
new file mode 100644
index 000000000000..a61a7b186017
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-dax
@@ -0,0 +1,151 @@
+What: /sys/bus/dax/devices/daxX.Y/align
+Date: October, 2020
+KernelVersion: v5.10
+Contact: [email protected]
+Description:
+ (RW) Provides a way to specify an alignment for a dax device.
+ Values allowed are constrained by the physical address ranges
+ that back the dax device, and also by arch requirements.
+
+What: /sys/bus/dax/devices/daxX.Y/mapping
+Date: October, 2020
+KernelVersion: v5.10
+Contact: [email protected]
+Description:
+ (WO) Provides a way to allocate a mapping range under a dax
+ device. Specified in the format <start>-<end>.
+
+What: /sys/bus/dax/devices/daxX.Y/mapping[0..N]/start
+Date: October, 2020
+KernelVersion: v5.10
+Contact: [email protected]
+Description:
+ (RO) A dax device may have multiple constituent discontiguous
+ address ranges. These are represented by the different
+ 'mappingX' subdirectories. The 'start' attribute indicates the
+ start physical address for the given range.
+
+What: /sys/bus/dax/devices/daxX.Y/mapping[0..N]/end
+Date: October, 2020
+KernelVersion: v5.10
+Contact: [email protected]
+Description:
+ (RO) A dax device may have multiple constituent discontiguous
+ address ranges. These are represented by the different
+ 'mappingX' subdirectories. The 'end' attribute indicates the
+ end physical address for the given range.
+
+What: /sys/bus/dax/devices/daxX.Y/mapping[0..N]/page_offset
+Date: October, 2020
+KernelVersion: v5.10
+Contact: [email protected]
+Description:
+ (RO) A dax device may have multiple constituent discontiguous
+ address ranges. These are represented by the different
+ 'mappingX' subdirectories. The 'page_offset' attribute indicates the
+ offset of the current range in the dax device.
+
+What: /sys/bus/dax/devices/daxX.Y/resource
+Date: June, 2019
+KernelVersion: v5.3
+Contact: [email protected]
+Description:
+ (RO) The resource attribute indicates the starting physical
+ address of a dax device. In case of a device with multiple
+ constituent ranges, it indicates the starting address of the
+ first range.
+
+What: /sys/bus/dax/devices/daxX.Y/size
+Date: October, 2020
+KernelVersion: v5.10
+Contact: [email protected]
+Description:
+ (RW) The size attribute indicates the total size of a dax
+ device. For creating subdivided dax devices, or for resizing
+ an existing device, the new size can be written to this as
+ part of the reconfiguration process.
+
+What: /sys/bus/dax/devices/daxX.Y/numa_node
+Date: November, 2019
+KernelVersion: v5.5
+Contact: [email protected]
+Description:
+ (RO) If NUMA is enabled and the platform has affinitized the
+ backing device for this dax device, emit the CPU node
+ affinity for this device.
+
+What: /sys/bus/dax/devices/daxX.Y/target_node
+Date: February, 2019
+KernelVersion: v5.1
+Contact: [email protected]
+Description:
+ (RO) The target-node attribute is the Linux numa-node that a
+ device-dax instance may create when it is online. Prior to
+ being online the device's 'numa_node' property reflects the
+ closest online cpu node which is the typical expectation of a
+ device 'numa_node'. Once it is online it becomes its own
+ distinct numa node.
+
+What: $(readlink -f /sys/bus/dax/devices/daxX.Y)/../dax_region/available_size
+Date: October, 2020
+KernelVersion: v5.10
+Contact: [email protected]
+Description:
+ (RO) The available_size attribute tracks available dax region
+ capacity. This only applies to volatile hmem devices, not pmem
+ devices, since pmem devices are defined by nvdimm namespace
+ boundaries.
+
+What: $(readlink -f /sys/bus/dax/devices/daxX.Y)/../dax_region/size
+Date: July, 2017
+KernelVersion: v5.1
+Contact: [email protected]
+Description:
+ (RO) The size attribute indicates the size of a given dax region
+ in bytes.
+
+What: $(readlink -f /sys/bus/dax/devices/daxX.Y)/../dax_region/align
+Date: October, 2020
+KernelVersion: v5.10
+Contact: [email protected]
+Description:
+ (RO) The align attribute indicates alignment of the dax region.
+ Changes on align may not always be valid, when say certain
+ mappings were created with 2M and then we switch to 1G. This
+ validates all ranges against the new value being attempted, post
+ resizing.
+
+What: $(readlink -f /sys/bus/dax/devices/daxX.Y)/../dax_region/seed
+Date: October, 2020
+KernelVersion: v5.10
+Contact: [email protected]
+Description:
+ (RO) The seed device is a concept for dynamic dax regions to be
+ able to split the region amongst multiple sub-instances. The
+ seed device, similar to libnvdimm seed devices, is a device
+ that starts with zero capacity allocated and unbound to a
+ driver.
+
+What: $(readlink -f /sys/bus/dax/devices/daxX.Y)/../dax_region/create
+Date: October, 2020
+KernelVersion: v5.10
+Contact: [email protected]
+Description:
+ (RW) The create interface to the dax region provides a way to
+ create a new unconfigured dax device under the given region, which
+ can then be configured (with a size etc.) and then probed.
+
+What: $(readlink -f /sys/bus/dax/devices/daxX.Y)/../dax_region/delete
+Date: October, 2020
+KernelVersion: v5.10
+Contact: [email protected]
+Description:
+ (WO) The delete interface for a dax region provides for deletion
+ of any 0-sized and idle dax devices.
+
+What: $(readlink -f /sys/bus/dax/devices/daxX.Y)/../dax_region/id
+Date: July, 2017
+KernelVersion: v5.1
+Contact: [email protected]
+Description:
+ (RO) The id attribute indicates the region id of a dax region.
--
2.41.0