Physical Addressing

Most of the library takes one or more physical addresses as parameter.

Generic format

The physical addresses are represented in generic format by the data-structure struct nvm_addr. One can construct an address by specifying the relative location within the device geometry down to the granularity of a sector.

Construct an address for sector 3 within page 11 in block 200 on plane 0 of LUN 1 in channel 4:

nvm_addr from_geo /dev/nvme0n1 4 1 0 200 10 3

Yielding:

0x04010003000a00c8: {ch: 04, lun: 01, pl: 0, blk: 0200, pg: 010, sec: 3}

The above hexadecimal-value can be given to any CLI command taking an 0xADDR as parameter.

Note

Addresses are zero-indexed, so channel 4 is the fifth channel

Note

C API address construction is done by assigning the members of struct nvm_addr

Device format

As the output from the device information shows, then there is a notion of a device format. The library user need not be concerned with the device format as the translation to device format is handled by the library for every part of the interface with the exception of the low-level command-interface nvm_cmd.

However, if one needs an address on device format for nvm_cmd or another tool such as nvme-cli, then the generic-format can be converted to device format using:

nvm_addr gen2dev /dev/nvme0n1 0x04010003000a00c8

Yielding:

gen: 0x04010003000a00c8: {ch: 04, lun: 01, pl: 0, blk: 0200, pg: 010, sec: 3}
dev: 0x00000000084c8053

Note

C API address format conversion is done using nvm_addr_gen2dev

Address scope

An address specifies the relative location of all parts of the geometry, channel, lun, plane, block, page and sector. However, not all parts of the library uses all location information. Most common uses are:

LUN address

Specify channel and LUN within the channel

Block address

Specify channel, LUN within the channel, plane within the LUN, and block within the plane

Sector address

Specify all relative locations of the geometry