Ubuntu Manpage: daxctl-create-device - Create a devdax device

NAME

       daxctl-create-device - Create a devdax device

SYNOPSIS

       daxctl create-device [<options>]

EXAMPLES

       •   Creates dax0.1 with 4G of size

           # daxctl create-device -s 4G
           [
             {
               "chardev":"dax0.1",
               "size":4294967296,
               "target_node":0,
               "mode":"devdax"
             }
           ]

       •   Creates devices with fully available size on all regions

           # daxctl create-device -u
           [
             {
               "chardev":"dax0.1",
               "size":"15.63 GiB (16.78 GB)",
               "target_node":0,
               "mode":"devdax"
             },
             {
               "chardev":"dax1.1",
               "size":"15.63 GiB (16.78 GB)",
               "target_node":1,
               "mode":"devdax"
             }
           ]

       •   Creates dax0.1 with fully available size on region id 0

           # daxctl create-device -r 0 -u
           {
             "chardev":"dax0.1",
             "size":"15.63 GiB (16.78 GB)",
             "target_node":0,
             "mode":"devdax"
           }

DESCRIPTION

       Creates dax device in devdax mode in dynamic regions. The resultant can also be convereted
       to the system-ram mode which arranges for the dax range to be hot-plugged into the system
       as regular memory.

       daxctl create-device expects that the BIOS or kernel defines a range in the EFI memory map
       with EFI_MEMORY_SP. The resultant ranges mean that it’s 100% capacity is reserved for
       applications.

OPTIONS

-r, --region=
Restrict the operation to devices belonging to the specified region(s). A device-dax
region is a contiguous range of memory that hosts one or more /dev/daxX.Y devices,
where X is the region id and Y is the device instance id.

-s, --size=
For regions that support dax device cretion, set the device size in bytes. Otherwise
it defaults to the maximum size specified by region. This option supports the suffixes
"k" or "K" for KiB, "m" or "M" for MiB, "g" or "G" for GiB and "t" or "T" for TiB.

The size must be a multiple of the region alignment.

-a, --align
Applications that want to establish dax memory mappings with page table entries
greater than system base page size (4K on x86) need a device that is sufficiently
aligned. This defaults to 2M. Note that "devdax" mode enforces all mappings to be
aligned to this value, i.e. it fails unaligned mapping attempts.

--input
Applications that want to select ranges assigned to a device-dax instance, or wanting
to establish previously created devices, can pass an input JSON file. The file option
lets a user pass a JSON object similar to the one listed with "daxctl list".

The device name is not re-created, but if a "chardev" is passed in
the JSON file, it will use that to get the region id.

Note that the JSON content in the file cannot be an array of
JSON objects but rather a single JSON object i.e. without the
array enclosing brackets.

-u, --human
By default the command will output machine-friendly raw-integer data. Instead, with
this flag, numbers representing storage size will be formatted as human readable
strings with units, other fields are converted to hexadecimal strings.

-v, --verbose
Emit more debug messages

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