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 8What is NVMe 9============ 10 11NVM Express (NVMe) is a register level interface that allows host software to 12communicate with a non-volatile memory subsystem. This interface is optimized 13for enterprise and client solid state drives, typically attached to the PCI 14express interface. It is a scalable host controller interface designed to 15address the needs of enterprise and client systems that utilize PCI express 16based solid state drives (SSD). The interface provides optimized command 17submission and completion paths. It includes support for parallel operation by 18supporting up to 64K I/O queues with up to 64K commands per I/O queue. 19 20The device is comprised of some number of controllers, where each controller 21is comprised of some number of namespaces, where each namespace is comprised 22of some number of logical blocks. A namespace is a quantity of non-volatile 23memory that is formatted into logical blocks. An NVMe namespace is equivalent 24to a SCSI LUN. Each namespace is operated as an independent "device". 25 26How it works 27------------ 28There is an NVMe uclass driver (driver name "nvme"), an NVMe host controller 29driver (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 31do necessary initialization to put the controller into a ready state at which 32it is able to scan all available namespaces attached to it. Scanning namespace 33is triggered by the NVMe uclass driver and the actual work is done in the NVMe 34namespace block driver. 35 36Status 37------ 38It only support basic block read/write functions in the NVMe driver. 39 40Config options 41-------------- 42CONFIG_NVME Enable NVMe device support 43CONFIG_CMD_NVME Enable basic NVMe commands 44 45Usage in U-Boot 46--------------- 47To use an NVMe hard disk from U-Boot shell, a 'nvme scan' command needs to 48be executed for all NVMe hard disks attached to the NVMe controller to be 49identified. 50 51To 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 58and print out detailed information for controller and namespaces via: 59 60 => nvme detail 61 62Raw 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 69Of 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 80Testing NVMe with QEMU x86 81-------------------------- 82QEMU supports NVMe emulation and we can test NVMe driver with QEMU x86 running 83U-Boot. Please see README.x86 for how to build u-boot.rom image for QEMU x86. 84 85Example 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 87