libnvme

This is the libnvme development C library. libnvme provides type definitions for NVMe specification structures, enumerations, and bit fields, helper functions to construct, dispatch, and decode commands and payloads, and utilities to connect, scan, and manage nvme devices on a Linux system.

The public specification is the authority to resolve any protocol discrepancies with this library. For more info on NVM Express, please see:

https://nvmexpress.org

Subscribe to linux-nvme@lists.infradead.org for linux-nvme related discussions and development for both kernel and userspace. The list is archived here:

https://lists.infradead.org/mailman/listinfo/linux-nvme

License

Except where otherwise stated, all software contained within this repo is currently licensed LGPL-2.1-or-later, see COPYING for more information.

Keith Busch 2020-02-06

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Dependency

libnvme depends on minimum Linux kernel version v4.15, which introduced the /sys/class/nvme-subsystem.

Build from source

Prerequisite

A minimal build depends on a set of build tools

• gcc
• ninja
• meson

Not all feature will be present with such configuration, e.g. the fabrics part of the library wont support authentication or TLS over the nvme-tcp transport.

To enable the optional features install following libraries

`/etc/nvme/config.json`` support:

• json-c (recommend)

Authentication and TLS over nvme-tcp:

• openssl
• keyutils

End point discovery for MI

• libdbus

Python bindings

• Python 3 interpreter
• Python 3 development libraries

Minimal on embedded builds

The reference implemention of the Meson specification is in Python 3. Installing or porting this dependency is not really feasible for embedded project. Though there are two project which implement the Ninja and the Meson API in pure C99

• samurai: https://github.com/michaelforney/samurai.git
• muon: https://git.sr.ht/~lattis/muon

The CI build helper script scripts/build.sh is able to setup and build this project in a minimal setup using samurai and muon and thus only depending on:

• gcc
• make
• git

scripts/build.sh -m muon

To compile libnvme

To configure the project:

meson setup .build

Which will default to build a shared library. To configure for static libraries call

meson setup --default-library=static .build

One nice feature of meson is that it doesn't mix build artifacts (e.g. *.o, *.so, etc.) with source code. In the above example, ".build" is the name of the directory where the build configuration as well as all the build artifacts will be saved. This directory can be named anything as long as it's not an existing source directory. To completely "clean" all the build artifacts, one need only delete the .build directory.

To compile:

meson compile -C .build

To install libnvme

To install libnvme:

meson install -C .build

To run unit tests

To run unit tests:

meson test -C .build

To purge everything

To completely clean all build artifacts, including the build configuration.

rm -rf .build

Supported build options

A few build options can be specified on the command line when invoking meson.

Option	Values [default]	Description
version-tag	none	Overwrite the git version string in the binary
htmldir	none	Installation directory for the HTML documentation
rstdir	none	Installation directory for the RST documentation
docs	[false], html, man, rst, all	Install documentation
docs-build	[false], true	Enable build documentation
python	[auto], enabled, disabled	Whether to build the Python bindings. When set to auto, the default, meson will check for the presence of the tools and libraries (e.g. swig) required to build the Python bindings. If found, meson will configure the project to build the Python bindings. If a tool or library is missing, then the Python bindings won't be built. Setting this to enabled, forces the Python bindings to be built. When set to disabled, meson will configure the project to not build the Python bindings. Example: meson setup .build -Dpython=disabled
openssl	[auto], enabled, disabled	Enables OpenSSL dependent features (e.g. TLS over TCP), adds build dependency on OpenSSL
libdbus	auto, enabled, [disabled]	Enables D-Bus dependent features (libnvme-mi: End point discovery), adds build dependency on libdbus
json-c	[auto], enabled, disabled	(recommended) Enables JSON-C dependend features (e.g. config.json parsing), adds build depdency on json-c
keyutils	[auto], enabled, disabled	Enables keyutils dependent features (e.g. authentication), adds build dependency on keyutils

See the full configuration options with

meson configure .build

Changing the build options from the command-line (i.e. w/o modifying any files)

To configure a build for debugging purposes (i.e. optimization turned off and debug symbols enabled):

meson setup .build --buildtype=debug

To enable address sanitizer (advanced debugging of memory issues):

meson setup .build -Db_sanitize=address

This option adds -fsanitize=address to the gcc options. The tests can then be run normally (meson test -C .build).

Note that when using the sanitize feature, the library libasan.so must be available and must be the very first library loaded when running an executable. If experiencing linking issues, you can ensure that libasan.so gets loaded first with the LD_PRELOAD environment variable as follows:

meson setup .build -Db_sanitize=address && LD_PRELOAD=/lib64/libasan.so.6 ninja -C .build test

It's also possible to enable the undefined behavior sanitizer with -Db_sanitize=undefined. To enable both, use -Db_sanitize=address,undefined.