doc/README.nvme

   1 #
   2 # Copyright (C) 2017 NXP Semiconductors
   3 # Copyright (C) 2017 Bin Meng <bmeng.cn@gmail.com>
   4 #
   5 # SPDX-License-Identifier:      GPL-2.0+
   6 #
   7
   8 What is NVMe
   9 ============
  10
  11 NVM Express (NVMe) is a register level interface that allows host software to
  12 communicate with a non-volatile memory subsystem. This interface is optimized
  13 for enterprise and client solid state drives, typically attached to the PCI
  14 express interface. It is a scalable host controller interface designed to
  15 address the needs of enterprise and client systems that utilize PCI express
  16 based solid state drives (SSD). The interface provides optimized command
  17 submission and completion paths. It includes support for parallel operation by
  18 supporting up to 64K I/O queues with up to 64K commands per I/O queue.
  19
  20 The device is comprised of some number of controllers, where each controller
  21 is comprised of some number of namespaces, where each namespace is comprised
  22 of some number of logical blocks. A namespace is a quantity of non-volatile
  23 memory that is formatted into logical blocks. An NVMe namespace is equivalent
  24 to a SCSI LUN. Each namespace is operated as an independent "device".
  25
  26 How it works
  27 ------------
  28 There is an NVMe uclass driver (driver name "nvme"), an NVMe host controller
  29 driver (driver name "nvme") and an NVMe namespace block driver (driver name
  30 "nvme-blk"). The host controller driver is supposed to probe the hardware and
  31 do necessary initialization to put the controller into a ready state at which
  32 it is able to scan all available namespaces attached to it. Scanning namespace
  33 is triggered by the NVMe uclass driver and the actual work is done in the NVMe
  34 namespace block driver.
  35
  36 Status
  37 ------
  38 It only support basic block read/write functions in the NVMe driver.
  39
  40 Config options
  41 --------------
  42 CONFIG_NVME     Enable NVMe device support
  43 CONFIG_CMD_NVME Enable basic NVMe commands
  44
  45 Usage in U-Boot
  46 ---------------
  47 To use an NVMe hard disk from U-Boot shell, a 'nvme scan' command needs to
  48 be executed for all NVMe hard disks attached to the NVMe controller to be
  49 identified.
  50
  51 To list all of the NVMe hard disks, try:
  52
  53   => nvme info
  54   Device 0: Vendor: 0x8086 Rev: 8DV10131 Prod: CVFT535600LS400BGN
  55             Type: Hard Disk
  56             Capacity: 381554.0 MB = 372.6 GB (781422768 x 512)
  57
  58 and print out detailed information for controller and namespaces via:
  59
  60   => nvme detail
  61
  62 Raw block read/write to can be done via the 'nvme read/write' commands:
  63
  64   => nvme read a0000000 0 11000
  65
  66   => tftp 80000000 /tftpboot/kernel.itb
  67   => nvme write 80000000 0 11000
  68
  69 Of course, file system command can be used on the NVMe hard disk as well:
  70
  71   => fatls nvme 0:1
  72         32376967   kernel.itb
  73         22929408   100m
  74
  75         2 file(s), 0 dir(s)
  76
  77   => fatload nvme 0:1 a0000000 /kernel.itb
  78   => bootm a0000000
  79
  80 Testing NVMe with QEMU x86
  81 --------------------------
  82 QEMU supports NVMe emulation and we can test NVMe driver with QEMU x86 running
  83 U-Boot. Please see README.x86 for how to build u-boot.rom image for QEMU x86.
  84
  85 Example command line to call QEMU x86 below with emulated NVMe device:
  86 $ ./qemu-system-i386 -drive file=nvme.img,if=none,id=drv0 -device nvme,drive=drv0,serial=QEMUNVME0001 -bios u-boot.rom