From: Leon Romanovsky <leonro@xxxxxxxxxxxx> Reflect latest changes in udev rules regarding stable names assignment. Signed-off-by: Leon Romanovsky <leonro@xxxxxxxxxxxx> --- Documentation/udev.md | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+) diff --git a/Documentation/udev.md b/Documentation/udev.md index 002340cd..f0dc4ca4 100644 --- a/Documentation/udev.md +++ b/Documentation/udev.md @@ -147,3 +147,34 @@ In their unit files. `rdma-hw.target` is also a synchronization point that orders after the low level, pre `sysinit.target` RDMA related units have been started. + +# Stable names + +The library provides general utility and udev rule to automatically perform +stable IB device name assignments, so users will always see names based on +topology/GUID information. Such naming scheme has big advantage that the +names are fully automatic, fully predictable and they stay fixed even if +hardware is added or removed (i.e. no reenumeration takes place) and that +broken hardware can be replaced seamlessly. + +The name is combination of link type (Infiniband, RoCE, iWARP or OPA) +and the chosen naming policy, like NAME_KERNEL, NAME_PCI, NAME_GUID +or NAME_FALLBACK. Those naming policies are controlled by udev rule +and can be overwritten by placing own rename policy udev rules into +/etc/udev/rules.d/ directory. + + * NAME_KERNEL - don't change names and rely on kernel assignment. This + will keep RDMA names as before. Example: "mlx5_0". + * NAME_PCI - read PCI location and topology as a source for stable names, + which won't change in any software event (reset, PCI probe e.t.c.). + Example: "ibp0s12f4". + * NAME_GUID - read system image GUID information in similar manner to + net MAC naming policy. Example "rocex525400c0fe123455". + * NAME_FALLBACK - automatic fallback: NAME_PCI->NAME_GUID->NAME_KERNEL + +No doubts that new names are harder to read than the "mlx5_0" everybody, +is used to, but being consistent in scripts is much more important. + +There is a distinction between real devices and virtual ones like RXE or SIW. +For real devices, the naming policy is NAME_FALLBACK, while virtual devices keep +their kernel name. -- 2.19.1
