On systems using the Mellanox ConnectX adapters, the driver does not load the InfiniBand and RMDA modules at boot time, resulting in a failure to detect the adapter when using RDMA and InfiniBand related tools, such as ibstat. Errors typically display as follows:

ibpanic: [26013] main: stat of IB device 'mthca0' failed: No such file or directory

This issue results because although the mlx4_core and mlx5_core drivers are included in the initramfs to facilitate PXE boot, the InfiniBand and RDMA modules are not. If you need the driver for PXE boot, you can reload the driver manually after boot to trigger the RDMA hotplug sequence, for example:

# modprobe mlx5_core

If you do not require the mlx4_core or mlx5_core driver for PXE boot, you can remove these drivers from the initramfs and they are loaded after boot, as required, and the RDMA hotplug sequence is triggered normally. To remove the drivers from the initramfs, create /etc/dracut.conf.d/10-mlx_dracut-denylist.conf to include the line:

omit_drivers+=" mlx4_* mlx5_* mlxfw "

After you have done this, rebuild the initramfs by running:

# dracut -f

The changes take effect after reboot.

(Bug ID 31353413)