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How to use

Basics

Check out the Linux kernel

git clone https://github.com/OpenChannelSSD/linux.git

Configure it to at least include

CONFIG_LIGHTNVM=y
CONFIG_BLK_DEV_NULL_BLK=m
CONFIG_BLK_DEV_NVME=m

Initialize using null_blk driver

Instantiate the module with the following parameters

queue_mode=4 gb=4 nr_devices=1 lightnvm_num_channels=1

That will instantiate the LightNVM driver with a 4GB SSD, with a single channel. You can see that it was instantiated by checking the kernel log.

dmesg |grep lightnvm

where the output should be similar to

[    0.359255] lightnvm: pools: 1
[    0.359773] lightnvm: blocks: 512
[    0.360364] lightnvm: pages per block: 256
[    0.361037] lightnvm: append points: 1
[    0.361663] lightnvm: append points per pool: 1
[    0.362423] lightnvm: timings: 25/500/1500
[    0.363081] lightnvm: target sector size=4096
[    0.363779] lightnvm: disk flash size=4096 map size=4096
[    0.364665] lightnvm: allocated 131072 physical pages (524288 KB)
[    0.365740]  nullb0: unknown partition table`

Instantiate using NVMe using QEMU

If you have a LightNVM-compatible device, simply plug it in and it should be found. If you don't, then you can use the LightNVM-enabled QEMU branch to prototype with.

It's based on top of Keith Busch's qemu-nvme branch that implements a NVMe compatible device.

QEMU Installation

Get the source from

git clone https://github.com/OpenChannelSSD/qemu-nvme.git

and configure the QEMU source with

./configure --enable-linux-aio --target-list=x86_64-softmmu --enable-kvm

then make and install

Configure QEMU

Create an empty file to hold your NVMe device.

dd if=/dev/zero of=blknvme bs=1M count=1024

this creates a zeroed 1GB file called "blknvme". From there, you can boot your favorite Linux image with

qemu-system-x86_64 -m 4G -smp 1,cores=4 --enable-kvm -hda YourLinuxVMFile -append "root=/dev/sda1"
-kernel "/home/foobar/git/linux/arch/x86_64/boot/bzImage"
-drive file=blknvme,if=none,id=mynvme
-device nvme,drive=mynvme,serial=deadbeef,namespaces=1,lver=1,lchannels=1,nlbaf=5,lba_index=3,mdts=10

Where you replace YourLinuxVMFile with your preinstalled linux virtual machine. LightNVM is enabled with lver=1. The number of LightNVM channels is set to one, and the last part defines the page size to be 4K.